A319 / C337, St Petersburg-Clearwater USA, 2021

A319 / C337, St Petersburg-Clearwater USA, 2021

Summary

On 29 April 2021, the crew of an Airbus A319 which had just taken off from runway 18 at St Petersburg saw a Cessna M337 about to cross their intended track close to the same height and levelled off to ensure they passed beneath it achieving a 100 feet separation. The conflict was attributed to the controller’s general loss of situational awareness and his failure to properly scan airspace in the vicinity of the airport. The Cessna 337 pilot’s failure to fly at the standard circuit height or track downwind at the standard distance from the runway was deemed contributory.

Event Details
When
29/04/2021
Event Type
HF, LB, LOS
Day/Night
Day
Flight Conditions
VMC
Flight Details
Type of Flight
Public Transport (Passenger)
Intended Destination
Take-off Commenced
Yes
Flight Airborne
Yes
Flight Completed
Yes
Phase of Flight
Climb
Flight Details
Type of Flight
Private
Take-off Commenced
Yes
Flight Airborne
Yes
Flight Completed
Yes
Phase of Flight
Descent
Location - Airport
Airport
General
Tag(s)
Aircraft-aircraft near miss, PIC less than 500 hours in Command on Type, CVR overwritten, Visual Approach, PIC aged 60 or over
HF
Tag(s)
Procedural non compliance
LB
Tag(s)
Accepted ATC Clearance not followed, Manual flight
LOS
Tag(s)
Accepted ATC Clearance not followed, Required Separation not maintained, Level Bust, Near Miss, VFR Aircraft Involved
Outcome
Damage or injury
No
Non-aircraft damage
No
Non-occupant Casualties
No
Off Airport Landing
No
Ditching
No
Causal Factor Group(s)
Group(s)
Aircraft Operation
Air Traffic Management
Safety Recommendation(s)
Group(s)
None Made
Investigation Type
Type
Independent

Description

On 29 April 2021, an Airbus A319 (N306NV) being operated by Allegiant Air on a scheduled domestic passenger flight from St Petersburg-Clearwater to Norfolk VA as AAY803 had just taken off from runway 18 in day VMC when the crew saw a Cessna M337 on a potentially conflicting flight path. The A319 crew immediately levelled off and as a result passed beneath the other aircraft with a 100 foot separation before resuming their departure climb. The inbound Cessna M337 had been on a local flight and had been cleared downwind for a landing on intersecting runway 22.

Investigation

A Serious Incident Investigation into this “near mid air collision was carried out by the US National Transportation Safety Board (NTSB). Relevant data was obtained from the A319 FDR, recorded radar and recorded ATC communications and from statements and interviews of the pilots and controllers involved.

The 51 year-old A319 Captain had an “estimated” total of 6,454 hours flying experience of which 6,111 hours were on type and the 37 year-old First Officer who was acting as PF had an “estimated” total of 4,224 hours flying experience of which 2,270 hours were on type. Both these experience figures were provided by Allegiant Air who advised that they were based on flight times since 2013, those prior to 2013 being unavailable. The 69 year-old Cessna 337 pilot was a local resident and Private Pilot Licence (PPL) holder who had a total of 2,100 hours flying experience of which 341 hours was on type.

What Happened

Ten minutes prior to the A319 beginning its takeoff, the Cessna 337 had taken off for a short flight in the local area. It then returned for a full stop landing and a visual circuit join for runway 22 downwind left hand was approved by TWR and a transponder squawk given. It then became apparent to the controller that an Airbus A319 would shortly be departing from intersecting runway 18 and the Cessna 337 pilot was instructed to “turn left 20°” and join right hand downwind instead and acknowledged the instruction.  

One minute after this acknowledgement had been received, the controller cleared the A319 to takeoff from runway 18 and takeoff was commenced. Soon afterwards, the A319 transmitted to TWR “Allegiant 803 what’s with the aircraft that we almost just hit” and received the response that “there’s traffic at 10 o’clock but they’re turning northeast bound and they’re no factor and there was traffic that flew over the runway at 1,000 feet towards the approach end and they’re in a right downwind for runway 22, is that who you are talking about”. The A319 crew responded with “yeah, we had to level off we were climbing right into them”. FDR data confirmed the account of a sudden level off which included a momentary recorded descent rate of 32 fpm and a restart of the climb one second later. It also showed that the First Officer’s level off action had begun 4 seconds after the main landing gear left the ground.

The A319 Captain’s subsequent statement stated that “they were light and rotated about five hundred feet before the old runway 9/27” (visible with ‘X’ marks on the annotated diagram depicting the conflict below). He had then called “positive climb” and the First Officer responded with “gear up”. He noted that since the aircraft was lightly loaded, they were climbing very fast and as he had reached over for the gear he had seen an aircraft about to cross their track at about 200 feet higher in his one-thirty (clock) position and immediately called the First Officer to level off, pointed out the traffic and left the gear down. Having passed beneath it, the climb was recommenced and he called TWR to report the near miss. The controller responded that “the aircraft was at 1,000 feet” and instructed the flight to change frequency to departure which they acknowledged and did.

FAA-certified radar position data with Mode ‘C’ altitudes recorded at Tampa showed that the Cessna 337 was actually flying downwind at 300 feet agl and on a track which was less than 250 metres from the centreline of runway 22 when it overflew runway 18 by which time the A319 levelled off at 200 feet agl. As a result solely of the rapid initiation of avoiding action by the A319, the two aircraft had been laterally separated by just over 100 metres as they crossed tracks.

A319-C337-StPetersburg-Clearwater-2021-LOS

The closest lateral separation (just over 100 metres) with 100 feet vertical separation. [Reproduced from the Official Report]

Why It Happened

The TWR controller had not made any attempt to monitor the Cessna 337 right hand circuit join before issuing takeoff clearance to the A319. In the absence of any notified airport-specific difference from a standard 1000 foot visual circuit normally applicable in such circumstances, the controller appeared to have assumed that the Cessna was flying the right hand downwind leg at or about the standard distance from the landing runway and that this leg was being flown at or about 1000 feet agl. Had this been the case, the two aircraft would have been safely separated. 

The relevant generic content of the FAA ‘Aeronautical Information Manual’ (AIM) had been comprehensively ignored by the Cessna 337 pilot and both his and the controller’s calls shortly after the conflict had occurred actively (the controller) and passively (the Cessna 337 pilot) had denied that there had been any ‘close call’ between the two aircraft. Although the Shift Supervisor had been present in the control room at the time, they appeared to have been unaware of the conflict developing or occurring. 

The Probable Cause of this “near midair collision” was formally documented as “the air traffic controller’s failure to properly scan the runway and local area and their general loss of situational awareness

A Contributory Factor was identified as “the Cessna 337 pilot's poor decision making when he failed to fly the standard downwind leg distance from the runway or maintain the standard traffic pattern altitude”.

The Final Report was published on 22 September 2023.

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