RIP Crew of UPS MD-11 Crash in Louisville, Kentucky
RIP to the crew of the UPS MD-11 that crashed on takeoff in Louisville, KY.One senior airline pilot believes that the incident possibly began on takeoff in the gap between V1 and V-rotate speeds where an airplane is most vulnerable to engine failure. V1 is the speed where a decision must be made to continue the takeoff or abort. Aborting at V1 is still slow enough to stop before the end of the runway. Exceeding V1 speed obligates the crew to take off lest they depart the end of the runway. V-rotate is the speed where the nose is lifted to begin the climb off the ground.
On takeoff the MD-11 is full of fuel (35,000 gallons in this case at 6 lbs. per gallon) and at full power. Near max gross weight and with no further power to add, an airliner might lift a few feet off the ground in ground effect but settling down off the runway at high speed and full of fuel is a gamble most are likely to lose. For commercial jet aircraft, the maximum landing weight and the maximum takeoff weight are different, with the landing weight being a bit lower. A jet taking off at max gross weight and then wanting to return to the airport right away must either dump fuel or loiter nearby to burn off excess fuel. Landing too heavy may result in blown tires and/or landing gear damage. Loss of a main landing gear will result in the wing and possibly the engine contacting the ground which can result in the plane pivoting abruptly and possibly tipping over.
What Happened in Louisville? Pilot Reacts to Crash Footage
The above explanation rests on the cited airline pilot’s early assessment as well as basic aeronautical knowledge. I watch this pilot’s videos regularly and have come to trust his content. The NTSB is investigating and will issue a final report in due time. Explanations prior to the release of the final report will contain some amount speculation. However, some speculators are better than others.
The senior airline pilot on YouTube referred to the fire as an “uncontained” engine fire. A contained engine fire within the engine cowling is almost always survivable, but when the entire engine with pylon breaks off at the wing mount as with this MD-11, the airplane will naturally want to yaw and roll over the missing engine as in what happened. It’s reminiscent in some ways of the engine fire and crash of the Air France Concorde crash in Paris in 2000. In the Concorde crash, a left engine sucked in some tire fragments from a blown tire after running over debris on the runway.
The loss of the entire left engine with pylon resulted in the American Airlines flight 191 crash at Chicago O’Hare in 1979. The cause was due to stress fracturing and failure in the attachment assembly between the left engine pylon and the wing during engine maintenance. Instead of disconnecting just the engine, the airline found it saved 200 hours of maintenance time to disconnect the pylon from the wing instead of detaching only the engine.
Aircraft structures are designed to withstand forces along certain directions. For example, a bird impacting and entering the cockpit may not be a major design criterion. Side loading of a landing gear from landing partially sideways results in forces that otherwise may be tolerated, but lateral forces may overstress the gear assembly, destroying the tires adding to the fa8lure sequence. A pressurized aircraft is designed to withstand internal air pressure and pressure cycling, but not necessarily from other directions beyond some conservative specification. Wings are designed to withstand a certain amount of positive and negative g-forces as well as some flexure, but beyond these specs, the crew are airline test pilots expanding the performance envelope.