Aircraft ground collisions are unfortunately becoming quite common place. In almost all cases, they either involve ramp workers misjudging turns, or aircraft taxiing and coming into contact with improperly parked aircraft or ground equipment, or simply taxiing down an unapproved taxiway and hitting an object such as a light pole. However once aircraft move out of the ramp area, incidents like those tend to be very rare.
On July 27, 2024, there were a number of Delta Air Lines aircraft lined up for departure from runway 16 Left. For context, a Delta Airbus A220-100 (DL1304 flying to Santa Ana) was first in line. At the time, weather conditions were not favorable as there was a tailwind. As a result the crew required a few extra minutes to re-run their takeoff performance numbers to ensure they were within limits for a tailwind departure.
Pilots generally prefer headwind departures as it reduces both the takeoff ground speed and required distance to get off the runway. Tailwinds do the opposite, and each aircraft has its own tailwind limits based on the limitations of the airframe design. Factors like usable runway length and airline standard operating procedures (SOPs) also play a significant role in performance calculations.
Meanwhile, a Delta Boeing 737-900ER (DL2046 flying to Bozeman) third in line asked the tower air traffic controller to jump the queue so they could depart via the taxiway to their right (Hotel 12).
Delta 2046: Tower, Delta 2046 we have numbers for Hotel 12 departure if able.
Tower: Delta 2046, that’s fine, Runway – and you have access now?
Delta 2046: We can get in there.
Tower: Okay Delta 2046, the wind 360 at 4, Runway 16 left at Hotel 12, cleared for takeoff, turn right heading 290.
Unfortunately when the Boeing 737 turned onto taxiway H12, the left wingtip struck the tail section of another Delta aircraft just ahead of them, an Airbus A320-200 flying to Dallas-Fort Worth as a DL2677. Flight 2046 and 2677 were forced to return to the gates as a result of the collision.
You can listen to the whole interaction above. On a positive note, I commend the pilots for being so calm about the situation, especially those on board DL2677 just waiting in line minding their business. I know the crew on DL2046 must have said to themselves, “if only they we had a bit more patience”.
Completely avoidable
I understand the pressures pilots are under to get out on time, especially when the heads of many airlines tend to put too much emphasis on bumping up the numbers and on-time statistics. However with a limited view from the flight deck, and with no one on the ground to check that both aircraft had enough separation, this was clearly not a good call from the crew on board DL2046. It was quite apparent that even the tower controller could not help them visually assess the situation due to the distance between the tower building and the end of runway 16 Left.
It’s a gamble that did not go in DL2046’s favor, resulting in two flights being significantly delayed, and two aircraft having to be pulled out of service for inspection and remedial maintenance.
Featured image: Steve Knight/Flickr | CC BY 2.0 Generic