Pilot: The Mystery of Delta Flight’s Fuel Dump

Wire Service
By Wire Service
January 22, 2020US News
share
Pilot: The Mystery of Delta Flight’s Fuel Dump
A Delta Airlines plane. (Joe Raedle/Getty Images)

Shortly after takeoff from LAX at 11:32 AM on Jan. 14, Delta Flight 89, a Boeing 777-200 bound for Shanghai experienced an engine abnormality called a compressor stall. According to recorded transcripts of the flight during its departure, one of the pilots reported the event to air traffic controllers, along with a request to return to the airport 20 minutes after it had taken off.

It made its emergency landing, and then it made headlines: it had dumped thousands of pounds of jet fuel at a too-low altitude over a populated area that included six Los Angeles schools at recess, dousing children and others. Aviation officials were surprised at the pilots’ decision—particularly because in their transmission to air traffic control when they requested return, the pilots asserted that they would not need to dump fuel.

The Federal Aviation Administration (FAA) is investigating and on Jan. 17 four elementary school teachers from one of the affected schools sued Delta, accusing the pilots of failing to follow protocol. Delta spokesman Anthony Black said the airline would have no comment on the litigation.

Before we jump to conclusions one way or the other, my advice would be to wait for the FAA’s report. Meantime, as a longtime 777 pilot, I can shed some light on dealing with compressor stalls and fuel dumps.

First: What is a compressor stall? It happens when, essentially, the jet engine is ingesting too much air for it to compress, causing turbulent airflow within the engine. Under normal circumstances, because of the immense amount of static air sucked into the engine at the beginning of the takeoff roll, various valves open to relieve the pressure. Although the event is not unheard of, it is unusual in most modern jet engines. Most times the compressor stall occurs before the airplane even accelerates much beyond taxi speed, so pilots can easily abort the takeoff.

So, a compressor stall is announcing a problem internal to the engine that could show up as other, bigger problems further into the flight, such as engine failure or the inability of the engine to develop full power.

Often, a compression stall includes a loud, disconcerting bang, and sometimes a quick flame erupts from behind the engine, then quickly disappears. It’s similar to a backfire in an automobile. Once pilots reduce the power, as is part of normal procedure for the initial climb after takeoff, the event is usually over. The engine remains operating with no other immediate effects. No fire. No engine failure.

Because pilots sit so far forward of the engines, it is difficult for them to hear a compressor stall. Cockpit instrumentation and warnings are not activated for a compressor stall, other than perhaps some temperature fluctuations that most times don’t indicate readings beyond the danger zone. But it is not unusual for flight attendants to call into the cockpit to inform the pilots of a loud bang.

I listened to the pilots’ transmission with air traffic controllers from Delta Flight 89 in its entirety.

Because it was several minutes before one of the Delta pilots requested to return after reaching the flight’s assigned altitude of 8,000 feet, it seems to me that the compressor stall was troublesome, but not necessarily an immediate and perilous threat. The tone of subsequent transmissions from the pilot who made the remaining radio calls suggested that the stress level was high, but there was no indication that the airplane was in imminent danger. The captain made the prudent decision to return out of an abundance of caution.

delta airplane
A Delta Air Lines plane lands in a file photograph. (Mario Tama/Getty Images)

The crew’s real problem was that they were dealing with an airplane that was over its certified maximum landing weight because it was carrying the fuel load required to fly to Shanghai. A heavier airplane requires a faster speed to fly an approach. A faster speed translates into the need for a longer runway required to stop. And if a heavier airplane lands at higher than normal descent rate when it touches down, the possibility of structural damage could occur. The way to reduce weight quickly is to dump fuel out a nozzle in each wingtip.

All this said, as long as dry surface conditions exist, most runways at major airports can accommodate an overweight 777 without needing to dump fuel. The second transmission from Delta Flight 89 after the initial report of the problem was a request to land on Runway 25R, the longest runway at the airport. It was a great decision and most likely was part of the captain’s safety briefing to the other pilots before they even pushed back from the gate.

Because of the emergency situation, this crew most likely completed a compressor stall checklist, an overweight landing checklist, a fuel dump checklist, and a normal landing checklist—all time-consuming procedures.

So why did this crew decide to dump fuel? And more importantly, why did this crew appear not to have informed air traffic control after an affirmative reply that dumping would not be necessary? Honestly, I don’t have the answer. Assuming that an immediate return wasn’t necessary, if the pilots had told controllers that dumping was required, the flight likely would have been vectored out over the ocean to an area where the fuel particles would, for example, not land on people.

In the ATC transmissions (which I listened to carefully and involved numerous frequency changes as part of the landing process) you could hear that on two separate occasions while the flight was being directed back to LAX, the crew requested additional delays before being turned onto the final approach path for Runway 25R.

The delay indicates to me that the crew was waiting till the fuel was dumped down to an airplane weight that they had calculated to allow a comfortable enough margin of concrete available to allow the aircraft to stop before the end of the runway, given the airspeed at touchdown. (Remember that higher weights translate to higher approach speeds). It seems they had ample opportunity to inform ATC that dumping was in progress. Puzzling? It is. But as with all events of this nature, I’ll wait for the investigative process to be completed before passing judgment.

The-CNN-Wire™ & © 2020 Cable News Network, Inc., a Time Warner Company. All rights reserved.
ntd newsletter icon
Sign up for NTD Daily
What you need to know, summarized in one email.
Stay informed with accurate news you can trust.
By registering for the newsletter, you agree to the Privacy Policy.
Comments