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Monday
Jan132014

Safe Landings - January 2014

Autoflight Associated Loss of Situational Awareness

The following reports are all airline related, but very applicable to GA high technology airplanes.  Of the 16 hours of training required in a Flight Instructor Refresher Clinic, nearly six hours is spent on this one subject. 

ASRS continues to receive reports in which Flight Crews appear to focus on the autoflight system to the extent that situational awareness is reduced, sometimes during critical phases of flight. In the following reports, awareness of the aircraft’s actual flight path seems to have been compromised by:

• Attention to programming the autoflight system

• Assumption that the autoflight system is accomplishing the desired task despite input or mode errors

• Failure to reference other visual cues or raw data

In many of these reports, workload, confusion, unexpected situations, distractions and fatigue are seen as factors that may exacerbate autoflight related issues. Autoflight human factor issues are a particular concern when both pilots lose situational awareness. This may occur with greater frequency as flight crews are trained primarily or exclusively in the more passive task of autoflight system management. ASRS reports suggest that the ability to maintain real world awareness can be eroded by over-reliance on the highly dependable programmed control of the aircraft. With that in mind, perhaps the following incidents should be viewed as the result of human nature rather than human error.

Telling It Like It Is — One Captain’s Opinion

A confusing departure chart and what the Captain characterized as over-reliance on automation resulted in a track deviation and traffic conflict for this air carrier Flight Crew. The Captain elaborates on his assessment of automation dependency and cluttered charts.

Two major points here: 1) I’m tired of flying around with people who are predisposed to let LNAV and automation lead them around by the nose and, 2) charts have gotten ridiculous….

It was the First Officer’s leg. We were late, but I really try to provide a laid back, don’t rush CRM posture. We did all the things we were supposed to do, but I guess we didn’t spend 15 minutes reading every word on the NEWARK ONE 22L/R departure page. This chart is a triple folded, 10-inch wide encyclopedia. The important piece of information is what to do on takeoff, yet it’s practically hidden in a box towards the bottom of the page…. When you consider the congested airspace in that area, it’s critical that you don’t turn the wrong way after takeoff, but that’s exactly what we did. Why we did that, I don’t know. We’re human I guess. At 400 feet the First Officer said, “LNAV.” I furrowed my brow…and thought, “Okay, maybe I missed something.” But I went ahead and punched LNAV and looked down at the LEGS page on my side and saw LANNA at the top. I said something like, “That doesn’t sound right.” Meanwhile our VSI was pegged because we were climbing like a fighter since we only had twenty-some people onboard.

While we were in the right turn, obviously towards the wrong place…I’m feeling like this is not going well while the First Officer is climbing and turning right toward an aircraft crossing our nose from left to right. He’s still a bit away, but…this looks like it’s going to be unusually close. I say…“Watch that guy,” pointing at the traffic, when I hear Departure say, “Did Tower give you a heading?” All my senses now tell me my first gut feeling was correct and I answer, “Ah, we’re checking,” while Departure rapidly rattles off, “Stop at 4,000 feet; turn left to 270; traffic 12 o’clock.” I told him we had the traffic in sight and he says, “You guys need to be careful.”

So, back to point number one. When I first was blessed to be a part of this fine group of pilots, the Captains I flew with all told me, “Never trust that box.” And we didn’t. We used our brains to fly the airplane. Now however, we bow to that thing! This is the second time this has happened to me and yes, of course it’s “my fault,” but both times it’s because [pilots] just let LNAV lead them around. These are not RNAV departures, they are ‘heading’ departures, but we’ve brainwashed everyone to think, “Just hit LNAV and it will be all right.” It’s not. Please don’t tell me, a “proper briefing” would’ve solved all this because we’ve reached briefing overload. [Pilots] are more worried about doing all the briefings than paying attention to actually flying the airplane….

The First Officer didn’t see the traffic because he was face down in the instrument panel following the FD LNAV guidance. When all this happened, his first reaction was to put on the autopilot and start reading the departure chart to see where we screwed up. I had to ask him to let it go until we got higher.

Managing the Automation — More or Less?

An A320 First Officer’s focus on managing the automation led to an approach deviation that prompted a warning from the Captain and triggered ATC low altitude alerts. Proper programming and proper use of the automation might have eliminated the problems in this incident, but errors can be made and systems can malfunction. Situational awareness will save the day (or the dark and stormy night).

In the transition to the visual (backed up by the ILS), I thought I needed to cross [the Outer Marker] at 1,600 feet, placing the aircraft high on profile. I selected 1,800 feet/minute [descent] Vertical Speed to intercept the glide slope from above. As the Captain crosschecked he realized the aircraft was low on profile. At that time (approximately 1,600 feet), I disconnected the autopilot, arrested the descent, and maintained level flight until re-intercepting the glide slope (at approximately 1,400 feet)…. Approach Control and Tower informed us they had received a low altitude alert. Spend more time flying the aircraft and less time managing the automation. Had I tracked the LDA course and flown a visual approach it would have eliminated a high workload in a time-compressed situation.

“We Were Supposed To Be Descending”

It is interesting to note that situational awareness, in this case knowing that the aircraft was climbing when it should have been descending, was not mentioned by the reporter as an element in preventing future deviations. The B737-700 Captain focused instead on automation as the sole remedy.

We were given clearance to descend to FL240…. As we began the descent, the VNAV would not engage. I tried entering a lower altitude so the VNAV would engage…. I thought we were all set and that the descent was occurring. I later noticed we had climbed from about 27,600 feet to 30,000 feet. We were supposed to be descending to FL240. After I noticed the aircraft level off, I used Vertical Speed to continue the descent…. We should have monitored our FMC entries better. This would prevent what had occurred.

 

Friday
Dec062013

Safe Landings: December 2013

Expectation Bias

An expectation of what we think will happen has a tendency to alter what we subsequently observe or hear. This expectation bias is often exacerbated by confirmation bias, i.e., being focused on information that confirms one’s interpretation of a situation while giving less weight to that which contradicts it. The following ASRS reports show how mistakes can be made when Pilots and Controllers are carried along by familiar cues, slip into habit patterns, and become less aware of changes to what is “expected.”

“I Absolutely… Heard Our Callsign”


Circumstances confirmed this CRJ900 crew’s expectations to the point where the First Officer “absolutely” believed that their callsign was given with a takeoff clearance. The Captain, also hearing what he expected to hear, started to taxi across the hold short line before a voice from the Tower raised a red flag.

• As we approached the end of the runway, an air carrier flight in front of us was cleared for takeoff. We pulled up to the hold short line and stopped. We were the only aircraft in the Number One position at the end of the runway. There was nobody across the runway waiting to depart from the east side. It was just us and a few aircraft behind us…. I heard Tower clear us to, “Line up and wait” and I read back the clearance on the Tower’s frequency. The Captain called for the line-up checklist and started to advance the thrust levers. As the nose of the aircraft crossed the hold short line, somebody transmitted on the Tower frequency, “Who’s taking the runway?” This immediately raised a red flag and before I could say anything, the Captain brought the aircraft to an abrupt stop. We were barely across the hold short line and the Tower said something to the effect of, “Who is Number One at Runway 32?” I replied with our flight number and stated, “You cleared us to line up and wait on 32.” The Tower Controller replied, “Actually, I cleared another flight (it was behind us) to line up and wait on 32, but if you’re Number One for the runway, line up and wait, Runway 32.”

We…departed uneventfully. In retrospect, I can see that expectation bias was clearly in play. I absolutely believed that I heard our call sign being cleared to line up and wait and did not consider the possibility that the Tower had inadvertently cleared the aircraft behind us to line up and wait. Interestingly, both of us were positive that the clearance was for us, so checking with the other pilot would not have yielded a different result. In the words of the Captain, this was a wake-up call for both of us to ensure we are more alert to all clearances and transmissions. Bottom line, I made a mistake and erroneously responded to another aircraft’s clearance.

Familiarity Breeds Expectations

Even after briefing a departure with a specific reminder about maintaining runway heading to an assigned altitude, this Air Carrier Crew was “predisposed” to turn earlier, just as they had on previous departures.

• Non-towered airport procedures were reviewed and thoroughly briefed to include the Obstacle Departure Procedure (ODP). The ATC clearance received at the end of the runway stated, “You are released; fly runway heading; maintain 5,000; direct your first NAVAID; as filed; expect FL340 ten minutes after departure; departure frequency…” The First Officer was flying and briefed, “Runway heading to 5,000 feet.” The takeoff was uneventful with a strong crosswind out of the south and significant weather to the east and north. As Pilot Not Flying, I made the final call on CTAF (Common Traffic Advisory Frequency) that we were departing the airport airspace and would be turning west. I contacted Center as the First Officer entered a right bank at 2,100 feet MSL to proceed on course. Center immediately answered my check-in and asked if we were maintaining runway heading. We had turned approximately 30 degrees right and I directed the First Officer to turn immediately back to 090 degrees. I told Center we were executing the ODP and turning back to runway heading. He replied, “OK” and said we could maintain current heading which by then was back to runway heading. About 30 seconds later Center said “Radar Contact” and gave us a right turn direct, as filed… For me, I was predisposed for the right turn on course after the ODP since that was the standard clearance we received from Departure Control on my two previous departures. So even though we had just briefed “Runway heading to 5,000 feet” per our clearance, once airborne at the minimum turn altitude for the ODP, I expected a right turn. When the Pilot Flying turned right, it didn’t flag as an error like it should have. The clearance was copied, appropriately briefed and two folks let “the standard” occur when “non-standard” was the clearance. Don’t allow familiarity with a situation to set “expectation bias.”

 “I Heard What I Was Expecting to Hear”


It would seem improbable for someone to hear “right” when he or she is told, “left,” but the Pilot of a corporate jet heard what was expected, not what was said, and made a wrong turn. The incident is a clear lesson in the power of expectation bias to influence what we hear.

• I departed on Runway 7 and climbed on runway heading on Tower frequency…. During the climb, I was given instructions to, “Turn (left) heading 360” along with a frequency change. I was expecting a right turn when I heard the clearance… I commenced a right turn. This was a great example of how expectations can affect us. I heard what I had been expecting to hear and not what was said. With the close proximity of [another] airfield, which was departing to the west, I was anticipating a right turn back over the airport on departure. I am convinced this played a role in my believing that I had heard the command for a right turn. I made the frequency change and the new Controller issued an immediate left turn to course 360. The flight was continued without further incident.

Perhaps the best advice for avoiding the errors cited in this CALLBACK was given many centuries ago by the Chinese philosopher Loa Tzu, “Act without expectation

Thursday
Nov142013

Safe Landings - November 2013

General Aviation Fuel Management Issues

 While the ASRS receives an average of 35 General Aviation fuel starvation and fuel exhaustion incident reports per year, the NTSB investigates a significantly higher number of accidents related to fuel management. The voluntary nature of ASRS reports accounts for some of the difference in the number of reports, but the higher NTSB numbers also highlight another point — the fact that fuel management errors often lead to significant aircraft damage and/or personal injury. By taking heed of the lessons in the following ASRS reports, Pilots can help reduce fuel management errors and avoid the often costly results.

“I Aimed for a Thicket of Trees”

After a Student Pilot in a PA-44 set the fuel tank selector in the wrong position, only the quick action of the Instructor changed the event from a certain accident to an ASRS incident.

Lesson 1: Know how to operate the aircraft’s fuel tank selection panel.

The student…preflighted before the start of the lesson. While running the Start checklist, I observed some mishandling of switches such as engaging the starter when he meant to press the prime button and forgetting to turn the magnetos on prior to cranking the engine. During the run up, he demonstrated satisfactory procedures while checking the systems and briefing the takeoff and emergency procedures…. We taxied to the runway for the start of pattern work and were cleared for takeoff. While the student taxied onto the runway, I performed my own personal checks by visually confirming that all mags were on and both fuel selectors were in the ON position. 

After takeoff, the Student turned a left crosswind then downwind and started his Pre-Landing checks after the gear had been extended…. Abeam the runway, I requested a touch-and-go and read back the landing clearance…. The student reduced the throttles to 15 inches MAP (Manifold Absolute Pressure), added the first notch of flaps, and pitched for a 100 knot descent…. It was at that point that I noticed irregular left engine noise. Since we were flying on a fairly humid day, I promptly turned on the carb heat of the left engine and then the right. The left engine quit immediately following the application of the carb heat. I announced, “My controls,” took control of the aircraft and proceeded to adjust mixtures, props, and throttles full forward. At that point the right engine quit as well. I pitched for 88 knots and looked right and left in search of a place to land while declaring an emergency on Tower frequency. 

At this point we were approximately 1,000 feet AGL and somewhere just north of the…highway merger. I checked the mag switches to verify that they were on. Tower asked if we required equipment and I replied, “Yes, we can’t make the airport.” After ruling out any surrounding roads due to the amount of bank required to get to them, I aimed for a thicket of trees straight ahead. Reaching between the seats to verify that the fuel selectors were in the ON position, I found them both resting at the midpoint in the OFF position. I quickly pushed both fuel selectors full forward to ON and continued the glide. In the midst of preparing for a nose-high flare into the trees, both engines fired and started developing full power, pulling the aircraft up and away from the terrain. 

After reaching a safe altitude, I updated the Tower to let them know that we had regained power and would be landing on the runway. On final approach to land, the Student started reaching for the fuel selectors and yoke to which I responded, “Don’t touch anything. I am flying and will be taking this landing.” 

After parking and shutting down the aircraft, I questioned the Student on his actions. He stated, “I looked at the fuel selectors while on downwind; they looked wrong, so I moved them.”

 “I Flared and Landed in Rows of Soybeans”

A Pilot conducting skydiving operations in a light twin aircraft learned that a questionable visual inspection of the fuel tanks may not be the best way to confirm fuel gauge readings and could result in an unplanned arrival in the produce aisles. 

 

Lesson 2: Err on the side of caution. When it comes to fuel management, err much further on the side of caution.

This incident occurred while supporting skydiving operations. The flight was conducted in VFR conditions within a four-mile radius of the airport. The flight to altitude was uneventful and I released all the jumpers at an altitude of 13,000 feet. On the way down, I noticed a fluctuation in engine power from the right engine. Moments later, the power returned. I contacted [my base] and requested the Mechanic to meet me when I got down. I turned onto a four mile final with the landing gear down and locked, but flaps still up. At that point I saw the right engine fuel pump annunciator light come on. Moments later I felt the plane surge heavily and begin to slow. I powered up both throttle levers to arrest the loss of airspeed. The airplane immediately began to bank right and continued to do so despite counter control input. I determined the right engine was not producing power. At that point I was well short of the runway at about 500 feet AGL (or less), with the airspeed decreasing to around 80 knots. I immediately brought both throttles back to idle. This stopped the uncommanded turn and I was able to nose over a bit and select an open field east of the runway. I pushed the nose down to maintain my airspeed (still at 80 knots) and seconds later was able to clear some trees and head for a soybean field. As I cleared the trees, I selected the flap lever down, flared, and landed in the rows of soybeans. The roll out was short and surprisingly smooth. While still rolling, I feathered both engines and moved the condition levers to cut off…. 

I shut everything off, got out, and determined that the airplane had suffered no damage. I also determined that there were only trace amounts of fuel in each tank.

On pre-flight I was told by the pilot operating the plane the day before, that 40 gallons were flown off of the full nacelle tanks which contain 120 gallons total usable fuel. I visually confirmed that the tanks were approximately half-full, although this is very difficult to judge accurately. The fuel gauges in the cockpit also indicated ¾-full tanks on each side. After the off-field landing, I went back into the cockpit to check the fuel gauges again and they both still indicated ¼-full. 

In retrospect I can see my efforts to determine the fuel on board before the flight were inadequate, which lead to a fuel starvation event which nearly produced a low altitude VMC roll which would undoubtedly have ended me. I am still uncertain as to the exact discrepancy between perceived fuel and actual fuel onboard and I may never reconcile this. What is certain is that in the future I will err much further on the side of caution, especially when it comes to fuel management.

“All Was Normal Until Five Minutes After Takeoff”

The Pilot of an Experimental Homebuilt aircraft miscalculated the amount of fuel onboard and didn’t believe the tank that looked empty was actually empty. Unfortunately, he ran out of fuel while enroute to another airport… to get fuel. Fortunately, he shared a lesson in common (fuel) sense. 

Lesson 3: When a fuel tank shows no visible fuel, put fuel in, regardless of what you think is in the tank.

When I flew to the airport four days previously, I noted that I had about one hour of fuel remaining, i.e., a quarter of a tank. On the morning of the incident, I went to the airport to fly 20 miles south for fuel. In this airplane, no fuel will show up on inspection when there is less than a quarter tank. The tank gauges showed enough fuel and the previous trip should have allowed enough fuel. All was normal until five minutes after takeoff when the engine quit. [I] switched to the other tank and turned back to the airport. The engine restarted and ran for a minute and then quit. I attempted to return to the airport, but was unable. I elected to land alongside the highway…. 

Now I know that I should have added enough fuel to be sure there was no possibility of running out. I am not sure why my previous experience led me to believe that there was enough fuel…. When a fuel tank shows no visible fuel, put fuel in regardless of what previous experience tells one about how much should still be in the tank. No fuel visible means no fuel and not the four gallons that I “think” is still there.

 

Friday
Oct112013

Safe Landings - October 2013

Automation Issues

As autoflight system managers, Flight Crews are responsible for entering correct information into the flight management system, selecting the appropriate flight mode and monitoring the aircraft’s compliance with the desired flight path. As pilots, Flight Crews must maintain situational awareness, stay ahead of the aircraft, use good judgment, make sound decisions based upon training and experience, and do whatever is necessary (within the constraints of good airmanship) to put the airplane where it is supposed to be. These responsibilities apply not only to air carrier and corporate crews, but with the growing use of automation, to general aviation pilots as well.

This CALLBACK presents a few recent reports in which Air Carrier Flight Crews and a General Aviation Pilot share some lessons learned regarding automation issues

A Case of Complacency

Proper use of the autoflight system requires that pilots stay “in the loop” and maintain a proactive stance in regard to “flying” the aircraft. When the automation is consistently working as advertised, monitoring becomes more of a challenge. It becomes easier for pilots to enter a reactive state of mind and unconsciously disengage from anticipating the desired flightpath. In this case of autoflight complacency, the autoflight system went off track, but the A319 Flight Crew assumed everything was okay.

Approach cleared us for the visual approach to Runway 22L via direct to the Final Approach Fix. We inserted “Direct” to the fix in the box and verified NAV mode. Autopilot #1 and “APPR” modes were selected to intercept the localizer and glideslope at the Final Approach Fix. We were at 7,000 feet, the glideslope intercept altitude, three to four miles outside of the fix and east of the centerline for 22L. As we proceeded, still in NAV mode, the airplane remained left of a direct path to the Final Approach Fix. Both pilots were watching outside the aircraft. We were still tracking towards 22L, but not tracking to the fix anymore. Tower asked us to verify that we were landing on 22L. We acknowledged that we were. It was at this point that we saw we were going to intercept the 22L centerline inside of the final approach fix rather than at the fix. We landed without incident on 22L. 

We intercepted the LOC inside of the final approach fix instead of at the fix as we were cleared. We as a crew assumed the automation was doing what it was supposed to be doing. Being that we were cleared direct and the aircraft was confirmed to do this, we did not think the track was drifting off course (15 miles away). I have never seen this happen, but I will be more aware even in visual conditions.

Distracted and Dependent

Historically, distraction has been an element in many aviation incidents and accidents. Now, with the prevalence of automation, pilots are less actively engaged in flying the aircraft and it may well be that they are even more susceptible to distractions. 

An Air Carrier First Officer reported how a cockpit conversation, when combined with autoflight dependency, was enough to adversely affect their flight.

ATC cleared us to cross [a fix] on the arrival…at the expected, planned, and standard FL230. Our altitude was FL270. The Captain and I were talking. The fix started flashing indicating station passage. I recorded the fuel on the dispatch release and then realized that I had not begun descending. I told the Captain I had forgotten to descend and reduced power to idle, full spoilers, and adjusted vertical speed to 3,500 feet per minute. As I began descending, ATC told us to change to Center. We were 4,000 feet above our crossing altitude and leveled at FL230 five to six miles after the fix. 

It was a quiet morning with conversation on the flight deck to keep our minds active. My error as the flying pilot was not initiating the descent when assigned by ATC, not perceiving the [glideslope] guidance in my scan, and the Captain not catching my error in his monitoring cross check. I should, as I usually do, begin descending immediately when assigned crossing fixes. I should, if planning a three-degree descent, ask the Captain to remind me if he sees me not acting at the descent point. I should be aware that conversation, though good in keeping the mind active, also leads to distraction from flying responsibilities especially during low levels of activity and when the automation is “flying.”

“I Was Depending on My Autopilot…”

A BE35 Pilot interrupted monitoring the autopilot to deal with a radio problem. Fortunately, an Approach Controller wasn’t distracted from the responsibility to monitor the aircraft’s flight path.

Approach Control descended me to 3,000 feet. My heading was 160 degrees. I was told to maintain 3,000 feet and turn left to 060. I was depending on my autopilot to maintain my altitude and make the turn. The radio transmission from Approach was weak and barely audible. As I tried to ascertain the problem with the radio by turning the volume up and down and tapping on the radio, Approach Control said, “What are you doing? Where are you going? What altitude are you supposed to be at?” I then noticed that my altitude was approximately 2,000 feet. I stopped the descent and asked Approach, “What do you want me to do?” Approach gave me a left turn to 040 degrees, a right turn to base leg, and then a turn to final…. 

In a telephone conversation with ATC after landing, I was told that I had busted the assigned altitude and had come within 100 feet of another aircraft.

 

Monday
Jul152013

Safe Landings - July 2013

It has been said that the only voluntary act in aviation is the decision to take-off. Every action after take-off involves the skillful management of risk, the enjoyment of flight and a continuous stream of decisions that result in a safe landing.

In 1974, NASA created the Aviation Safety Reporting System (ASRS) to allow aviation professionals to share experiences in a frank, non-punitive manner. The ASRS structure allows pilots and other aviation professionals to file an anonymous report of an incident, error or occurrence that the contributor feels might be of value to others. These reports are gathered, analyzed and data based by NASA experts and made available to all interested parties as a tool for creating pro-active aviation safety programs. Additionally, NASA distributes an electronic publication, CALLBACK, which contains selected, de-identified, reports on a free subscription basis. In Flight USA is proud to reprint selected reports, exerted from CALLBACK, for our readers to read, study, occasionally laugh at, and always learn from. Visit http://asrs.arc.nasa.gov/ to learn how you can participate in the ASRS program.

RNAV Standard Terminal Arrival Route (STAR) Issues

According to the Aeronautical Information Manual (AIM) Chapter 5, Section 4 (Arrival Procedures), a STAR is an ATC coded IFR arrival route established for application to arriving IFR aircraft destined for certain airports. RNAV STAR/Flight Management System Procedures (FMSP) for arrivals serve the same purpose but are only used by aircraft equipped with FMS or GPS. The purpose of both is to simplify clearance delivery procedures and facilitate transition between en route and instrument approach procedures. A link to the full text of AIM Section 4 can be found at the end of this CALLBACK. ASRS receives a significant number of reports every month related to difficulties with RNAV arrival procedures. Examples of reported issues include:
•    Complexity of RNAV Optimized Profile Descents (OPDs)
•    Flight crew workload
•    Aircraft system compatibility or capability
•    ATC familiarity with aircraft performance and requirements
•    Procedure interruption and phraseology

The following ASRS report excerpts provide insight into some of the complexities surrounding RNAV arrival procedures and in particular, the problems associated with the “descend via” clearance.

IAD GIBBS1 RNAV Arrival


After having been cleared to “descend via” the GIBBS1 Arrival, the flight crew of an ERJ-170 was vectored off the arrival and uncertain as to their cleared altitude. Difficulty communicating with the busy controller to clarify the altitude forced a level off at an intermediate altitude until a new clearance could be provided.

• We were descending on the GIBBS1 RNAV into IAD between BBONE and KILMR when ATC assigned us a 020 heading for traffic. Our descent clearance was “descend via the GIBBS arrival” with no specific altitude given. I told my first officer to ask ATC what altitude he wanted us at and we got no reply. After two more unsuccessful tries to get an answer (the controller was busy), I leveled the aircraft at 11,000 feet, which was the altitude for the next fix. We finally got a reply to our questions and were told to continue to descend to 6,000 feet. ??As we had been cleared to “descend via” the STAR and, when vectored off of it, were no longer on the arrival, we had no guidance as to our cleared altitude. I’ve had this happen a couple times, with different altitudes given each time; some the same as the bottom altitude [on the STAR], some different. Anytime an aircraft has been given a “descend via” clearance and is later turned off the arrival, ATC needs to assign an altitude.

DCA TRUPS1

The Flight Crew of a CRJ-200, cleared to “descend via” the TRUPS1 Arrival, was understandably confused when given a heading change and then told to “continue” the arrival. The First Officer was the Pilot Flying and provides the first report on the incident.

• We were cleared to “descend via” the TRUPS1 Arrival and a second controller had cleared us to continue the arrival via the Runway 19 transition. Prior to reaching FRDMM waypoint, the controller told us to depart FRDMM heading 120, which seemed excessive. The [crossing] restriction at FRDMM is 8,000 feet. The pilot not flying queried the controller regarding the heading, but due to congestion he couldn’t get a word in edgewise. Finally, the controller issued new instructions to continue on the arrival. We were now at 8,000 feet and were past FRDMM [and were descending to comply with] the next crossing restriction of 6,000 feet [at STAND]. Shortly thereafter, the controller issued another heading change and took us off the arrival. Seconds prior, when [we were] on the arrival, we had continued our descent. I asked the captain to ask for clarification the controller replied that we were told to “continue on” the arrival and not to “descend via” the arrival. We quickly returned to 8,000 feet and were cleared for the River Visual shortly thereafter. The instructions were confusing at best. We were given a heading and, when we asked to confirm the heading, the response was changed to “stay on the arrival.” If the controller had said, “Stay on the arrival; maintain 8,000” the confusion would not have occurred.

From the captain’s report on the same incident:

• After crossing FRDMM, we started to descend to 6,000 feet per the STAR and at the same time the controller issued a heading change. I asked the First Officer if we should continue the descent since ATC just took us off the arrival and shortly after ATC asked us if we were still at 8,000 feet. I told him we were returning to 8,000 feet but thought we were still cleared to descend [as previously cleared] “via” the arrival. He explained that our new instructions were to “continue,” not to “descend via” the arrival.

PHX GEELA4


A controller report highlights the confusion that can occur when runway “transition” clearances are given in conjunction with RNAV arrivals.

• It was a busy arrival push into PHX this morning. With the GEELA4 RNAV arrival there are quite a few more transmissions that need to be made to ensure the pilot will do what we need him to do. If the pilot is to “descend via” the arrival, well that’s a straight-forward clearance. When we have to vector the aircraft for sequencing, the phraseology to put the aircraft back on the arrival is very confusing. An A320 was issued a clearance to cross GEELA at and maintain 12,000 feet and 250 knots. The pilot read this back correctly. The pilot was then issued, “Cleared for the GEELA4 Arrival, Runway 7R transition.” At no point was a “descend via” clearance given or read back. The aircraft then called PHX Approach and said he was descending “via” the arrival. ??We need to come up with some type of phraseology that will allow us to clear the aircraft for the arrival and transition without the pilot thinking he is cleared to “descend via” the arrival. It seems the pilots are associating the runway transition with a “descend via” clearance. Maybe we should give the runway transition on initial check in, if that is legal.

The complete AIM Section 4 Arrival Procedures can be found at: http:// www.faa.gov/air_traffic/publications/ atpubs/aim/aim0504.html

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