Assured vertical separation from terrain and other aircraft is one of the cornerstones upon which our national airspace system is built. For this reason, consistent and precise altitude control is critical to aviation safety. As important as adherence to an assigned altitude is, we humans stray from perfection for a variety of reasons and compliance is occasionally compromised. Once a deviation is recognized, prompt and accurate recovery to the correct altitude is essential.
This month, CALLBACK presents reports in which altitude deviations are triggered by multiple and varied issues. Seemingly minor errors in instrument settings, lapses in automation management, or a variety of human factors can have serious consequences, including terrain warnings, go-arounds, and ATC interventions. As you read these narratives, see if you can identify what the causes of the altitude deviations were, and witness how these crews recovered, utilizing their experience, knowledge, and diligent return to standard procedures.
Part 121 – Red over Red
This air carrier crew encountered several challenges and distractions on approach to SFO, resulting in an undesired automation mode and flight path. They successfully stabilized the approach and executed a safe landing.
■ ATC cleared us to descend via arrival then at EDDYY transition to the Tipp Toe visual 28L. We set 6000 ft. Approaching EDDYY, ATC told us to descend to 4000 ft. PF (FO) select LVL CHG. ATC advised us traffic Aircraft Y going to 28R. While looking for the traffic, ATC asked us to slow down to 210 kts and if we have the airport and bridge in sight and the traffic. Finally saw the traffic and told ATC airport, bridge and traffic in sight. ATC told us to maintain separation and cleared us for the visual. So we dialed in 1800 ft on the altitude window. We were focusing to make sure we don't overshoot the path because of the traffic threat. Then ATC told us to slow down to 180 then 160 kts until the bridge. PF (FO) asked for gear and flaps configuration to slow down. Confirmed no overshoot. PM (Captain) realized we were inside the approach and asked to set TDZ while heads down to do the configuration changes asked by PF. ATC told us to switch to Tower. Both did not realize we were still in LVL CHG. (Tasked saturated) Accomplished landing checklist before 1000 ft. Approximately 4 NM from the runway. I saw 4 red dots then realized we were low. It was around 750ft. I told the FO to disconnect autopilot and arrest the descent and hand fly [to] get back on path. Realized we never re-engaged VNAV. Tower on their side told us to check altitude. Corrected the issue. Re-established the glide path. Stable and cleared to land. Landed normally. Exited runway and taxied to the gate. Debriefed it. Identified [that] traffic was the primary reason for distraction and ATC due to multiple instructions at the same time.
Part 121 – Tune and Turn
This A330 pilot highlights two independent altimeter misconfigurations during descent. The oversight caused an undesired flight path and the crew executed a corrective maneuver.
■ I was the second Capt/Relief Pilot on a ZZZZ turn. The PF was the FO. The CA and FO both were utilizing Original Equipment Manufacturer (OEM) procedures and independently set the altimeter setting on descent. They both independently set the wrong altimeter setting. I did not catch the error as I was attempting to tune and turn on the pilot-controlled lighting at the field. They made all the correct altimeter related call outs to include the FAF crossing which they called accurate/checked. However the altimeter was set with the incorrect information and we were low on profile. This caused a low terrain warning on approach and a subsequent go-around. Further ops were normal.
Part 121 – The Way Away from San Jose
An air carrier crew reported leveling too soon after a change to their departure procedure. FMC loading and crosscheck was a factor.
■ We had a change to our departure SID, which caused us to redo the box. We did not go back and confirm CLB (climb) VIA the SID. There was an altitude of 3,000 ft. set in the window, when it should have been 15,000'. Neither one of us caught this. On departure, while level at 3,000 ft., NorCal [Approach] told us to climb to avoid an Altitude Alert for terrain. We caught our error and climbed before any Altitude Alerts happened in the cockpit. Suggestions: Better review of departure clearance, once the box has been redone.
Part 121 – Riding the Waves
This A319 pilot encountered severe turbulence resulting in a deviation from the cleared altitude.
■ …We encountered severe turbulence with updrafts that led the aircraft to an overspeed state. The flight was assigned to fly directly to the ZZZ VOR at FL350. There was no significant weather painted on the radar until we would reach the ZZZ VOR. The flight started to experience light occasional turbulence, so I decided to turn on the fasten seatbelt sign. About 38 NM east of ZZZ1 VOR, the aircraft altitude and airspeed began increasing rather quickly. I selected Mach 0.76 using selected airspeed knob to help reduce the airspeed increasing trend. Even through the aircraft engines were spooling back to attain Mach 0.76, the aircraft airspeed and altitude kept increasing, which led to the first overspeed warning. As we started to recover from the first upset, the aircraft entered another updraft and overspeed once again. I disconnected the autopilot and autothrust and rode the updraft upwards until it subsided at FL364. The event duration was about 20-30 seconds long. We immediately notified ZZZ Center of the upset event, which the controller began warning other aircrafts of the event in that area. We then contacted the flight attendants to learn about the status of the cabin. FA (Flight Attendant) A reported that no one was injured, none of the overhead bins ejected any of its contents, nor did any O2 masks drop from their PSUs. Since no one was injured and the flight was less than 200 NM from ZZZ, I did not find it necessary to declare an inflight emergency and continued to ZZZ where a safe landing was made.
Part 91 – A Momentary Lapse
This Falcon 900 Captain highlights the impact of fatigue on flight operations that led to an unintentional deviation in altitude and heading.
■ I got up for work at XA:00A.M. We would have four legs that day from our home airport, ZZZ, to ZZZ1, to ZZZ2, back to ZZZ1, then return home to ZZZ. Put the airplane to bed, drive home and back in the bed at XB:00 PM. Toward the end of a nineteen-hour day on the last leg from ZZZ1 to ZZZ we were cruising at 40,000 feet at night with no weather and smooth air. With 30 minutes to go, I decided to brief the approach into ZZZ with the other pilot. With our heads down looking at the iPad in my lap we began the approach briefing. The next thing I hear is the over-speed warning going off. I look up and we are in a nose low, 30-degree bank to the right. I've got a real-life unusual attitude at 40,000 feet at night! It was reflex to come back on the throttles, level the wings, pitch the nose up and climb back to 40,000 feet and get back on course. I was hoping that ATC didn't notice, but how could they not notice? By the time the over-speed warning went off, I lost 1200 feet of altitude and turned about 30 degrees off course. They said nothing. I said nothing. The adrenaline rush kept me alert for the rest of the flight. I am confident that fatigue was the main contributing factor…The rest of the flight was uneventful.
Part 91 – Yellow is not Mellow
This GA pilot learned an invaluable lesson for future flights.
■ I was flying a small aircraft for my first IFR solo cross country. … After departing JAX flying as filed at 6000 ft, I was asked to descend down to 4,000. I noticed I would be flying straight into the clouds - which by the looks of them seemed fine. I am an instrument rated pilot and current for IFR flying. I advised Orlando ATC [of] my request to deviate from buildups - they agreed. I deviated and then I requested an altitude change to 3000 to avoid the large build ups. I requested further deviations for weather avoidance several times but I was denied. I found myself in a rain shower which pushed my plane down due to the downdrafts. I was rapidly descending at this point. My airspeed was in the yellow and the aircraft was getting harder to control. While trying to maintain control over the aircraft, I advised ATC my concerns for the safety of flight, requesting an altitude change, I was denied again and advised to fly at 3,000 ft which I flew. I believe if I requested to stay at 6000 when the controllers gave me 4000 initially instead of descending down into the worse weather, I might not have broke[n] aircraft separation.
The reports featured in CALLBACK are offered in the spirit of stimulating thought and discussion. While NASA ASRS does not verify or validate reports, we encourage you, our readers, to explore them and draw your own conclusions.
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| ASRS Alerts Issued in April 2025 | |
|---|---|
| Subject of Alert | No. of Alerts |
| Aircraft or Aircraft Equipment | 4 |
| Airport Facility or Procedure | 10 |
| ATC Equipment or Procedure | 8 |
| Hazard to Flight | 1 |
| TOTAL | 23 |
| April 2025 Report Intake | |
|---|---|
| Air Carrier/Air Taxi Pilots | 5,308 |
| General Aviation Pilots | 1,585 |
| Flight Attendants | 1,559 |
| Military/Other | 729 |
| Controllers | 367 |
| Dispatchers | 258 |
| Mechanics | 188 |
| TOTAL | 9,994 |
■ Indicates an ASRS report narrative
[ ] Indicates clarification made by ASRS
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