Hello and Welcome Aboard!
In a recent event, the crew of a Boeing 777-200 took off from LAX and were headed to Asia. Most likely they were near maximum takeoff gross weight and they had a significant engine situation they had to handle. The unfortunate part of this story is that the fuel that was offloaded managed to make its way down near the ground, affecting many school children and teachers in the area below. Let’s dissect this so you may be able to have a better understanding of the factors involved.
There have been three times in my 35 years of flying when I lost an engine and had to fly the aircraft on just the other operating engine. It happened twice on takeoff and initial climb out and the other was in cruise. (Someday I will write another book detailing harrowing experiences I have had.) Needless to say, this gets our attention! These are the types of things we train for. The more experience we have, the more situations overall we have needed to safely handle.
When dealing with an event like this, the first priority is to make sure we can safely fly the jet. There is a saying in our aviator community, “Aviate, Navigate, Communicate”. We make sure that we can keep the jet upright and stable first. We consider performance such as keeping it at the current altitude, or possibly climbing a bit higher to keep away from structures and terrain if we can. There is usually delegation of duties between the pilots in these situations because we need all hands on deck! One pilot flies the jet while the other pilot declares an emergency with ATC and runs the emergency checklists.
We must navigate safely all while handling the emergency in order to stay away from terrain, obstacles, and other aircraft. We communicate with ATC, dispatch, maintenance, flight attendants, and passengers if we have the time. This is why occasionally you hear about emergencies where people say they did not hear from the pilots for awhile. It takes us time to first make sure we are safely able to fly, secure what we need to, navigate safely while making multiple critical decisions, then we can communicate.
The emergency checklists have us methodically go step by step for either trying to restart or re-engage a system, or they have us secure the failed system. Along with that, there are many other considerations that need to be made. How can we operate on just the remaining system or systems? What others aspects will affect our safety of flight? Can we operate the jet more securely by adjusting other related systems or configurations? Can we safely land back where we took off from or do we need to divert? These are all questions we must analyze and conclude. In some critical situations, we have little time to assess all the above.
In the case of operating a wide body twin-engine aircraft, heavy with fuel, we would want to get as much of that fuel off board as quickly as possible. This is because we need to get back down to our maximum structural landing weight.
These type of aircraft have fuel dumping capabilities. The single isle aircraft mostly used domestically do not have this ability. These long haul aircraft can carry as much as 45,000 gallons of jet fuel which is 303,000 pounds. The difference between maximum takeoff gross weight and maximum structural landing weight can be as much as 100,000 pounds. The aircraft are not certified to land significantly overweight. Serious damage can occur with this force impacting the runway. Things such as wing spar bends, landing gear going up through the structure, brakes catching fire, fuselage flex, etc can cripple the aircraft. This can also mean serious injuries to passengers and crew more importantly.
Certain aircraft have fuel dump rates of as much as 5400 pounds per minute, so off loading that fuel would could take as long as eighteen minutes. It is something we initiate in the cockpit with the fuel dump panel and nozzles spray the fuel out from the tanks. Some have preset limits that will auto shutoff the fuel dumping when reached. Having flown with failed engines before, hanging around in the sky for anymore time then absolutely necessary, is not something we want to be doing.
If we had lots of time to assess and make decisions, we could contemplate best places to select for offloading fuel. It most all cases, no matter where we are or what the circumstances, the fuel vaporizes in the air long before reaching any persons or property. Atmospheric conditions will either assist or hinder this process somewhat but normally it will dissipate within a few thousand feet. The FAA mandates no dumping of fuel below 2’000ft unless in dire emergency. Our recents events show that the crew was at 2300ft. In all my years of flying and asking many other pilots about it, none of us have ever heard of people on the ground experiencing fuel vapors from a jet aircraft.
Thankfully, all the passengers and crew aboard successfully and safely landed back in Lax. No one on the ground was injured or hospitalized and that is really what matters.
Thank you for joining me.
May you always have blue skies and smooth rides!