Frontier Airlines Flight 539
Airbus Industrie A319-111 · Incident: loss of control in flight during landing
From Los Angeles International Airport (LAX) to Denver International Airport (DEN)
Event
- NTSB case
- DEN07IA027
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Airbus Industrie A319-111
- Aircraft type
- Airbus A319
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N924FR
- Operator
- Frontier Airlines
- Onboard fatalities
- Unknown
- Route
- From Los Angeles International Airport (LAX), Los Angeles, CATo Denver International Airport (DEN), Denver, CO
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Landing · flare/touchdown
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control in flight
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Copilot/second pilot › Condition(s)/step(s) in error
- Flightcrew › Aircraft control, not possible
- Flt control syst, yoke/control stick › Activated
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
During the landing flare approximately 10 feet above ground level, the aircraft pitched nose down while the captain applied aft sidestick force. The rate that the nose descended seemed to be commanded and extremely smooth. The first officer wondered if he could have accidentally bumped his sidestick, but he did not think that action occurred. The captain landed the airplane with the main landing gear touching down first, and the captain's sidestick was once again responsive. The entire event took no longer than 2 seconds. No electronic centralized aircraft monitor (ECAM) warnings or other indications were noticed by the flight crew. Review of the digital flight data recorder (DFDR) data revealed that the captain's sidestick (left) was inoperative for approximately 1 second during the landing flare. During that time, the first officer's sidestick (right) pitch was in the neutral position. Less than one second after the captain's sidestick went to inoperative, both sidestick pitch positions went to approximately 14-16 degrees aft. Pitch data revealed a decrease in pitch of approximately 2 degrees during the event. The airframe manufacturer provided the following analysis of the incident: "Captain was Pilot Flying (PF). First officer was Pilot Non Flying (PNF). Manual approach and flare input from the PF were nominal. But, it appeared that [the] PNF take-over and priority pushbutton was pushed inadvertently for approximately 1 to 2 seconds during flare. As a warning, white arrow pointing to the right was displayed in front of captain (PF) and F/O (first officer) green light was lit in front of F/O (PNF). With the F/O priority button pressed, EFCS (Electrical Flight Control System) disregarded the captain inputs to the benefit of the F/O one. During this time, as no order (neutral) was applied on F/O sidestick, aircraft elevators returned to neutral position, leading pitch attitude to be reduced by 1.5 degrees. EFCS switched back to captain sidestick when priority switch was released, and captain resumed flare and landing uneventfully." According to operator, the non-flying pilot's hand should not be on the sidestick during critical phases of flight, such as the landing flare; however, the non-flying pilot should be in a position to takeover control, if required.
Probable cause
The inadvertent activation of the priority pushbutton on the sidestick by the first officer resulting in a nose down pitch and loss of aircraft control during the landing flare.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN07IA027
- Event ID
- 20061211X01766
- Case number
- DEN07IA027
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates, damage. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 8d16eade1226adf4a951a1f1fc3f6984948394e056ed9d6d431ddbbe67a62867; retrieved 2026-09-18T14:49:41.602Z.