Curious Crew Nearly Crashes DC-10
By Patrick Mondout
Have you ever flown a DC-10 at
39,000 feet with 115 passengers on board and been tempted to experiment
with autothrottle system - just to see what would happen? In late 1973, a
pair of curious National Airlines pilots did and their actions nearly cost
everyone on board their lives.
On November 3, 1973, National Airlines Flight 27 was operating as a
scheduled passenger flight between Miami and San Francisco with
intermediate stops at New Orleans, Houston, and Las Vegas. At about 4:40
p.m., while the aircraft was cruising at 39,000 feet 65 miles southwest of
Albuquerque, the No. 3 engine fan assembly disintegrated and its fragments
penetrated the fuselage, the Nos. 1 and 2 engine nacelles (which contain
those engines), and the right wing area. The resultant damage caused
decompression of the aircraft cabin and the loss of certain electrical and
The flight crew initiated an emergency descent, and the aircraft was
landed safely at Albuquerque International Airport 19 minutes after the
engine failed. The 115 passengers and 12 crewmembers exited the aircraft
by using the emergency slides.
As a result of the accident, one passenger died and 24 persons were
treated for smoke inhalation, ear problems, and minor abrasions.
The National Transportation Safety Board determined the probable cause
of this accident was the disintegration of the No. 3 engine fan assembly
as a result of an interaction between the fan blade tips and the fan case.
The fan-tip rub condition was caused by the acceleration of the engine to
an abnormally high fan speed which initiated a multiwave, vibratory
resonance within the fan section of the engine. The precise reason or
reasons for the acceleration and the onset of the destructive vibration
could not be determined conclusively.
A National DC-10-10 similar
to the one involved in this incident, as seen at
LAX in the mid Super70s..
Image courtesy of AirNikon.
Find more of his photos at Airliners.net
You want to try it and see?
However, it is clear that the captain and flight engineer's
irresponsible actions were to blame. They were experimenting with the
autothrottle system, which supplied the instruments that measure the
rotational speed of each engine's low pressure compressor. The cockpit
voice recording contains the following conversation just prior to the
number 3 engine exploding:
Flight Engineer: "Wonder, wonder if you pull the N1
tach will that, -- autothrottle respond to N1?"
Captain: "Gee, I don't know."
Flight Engineer: "You want to try it and see?"
Captain William Brookes, who had been a National Airlines pilot since 1946
and who should have known better responds, "Yeah, let's see
Flight Engineer: "You're on speed right now though."
Flight Engineer: "You know what I mean if your annunciated
speed - if you got, ---"
Captain: "Still got 'em."
Flight Engineer: "Well - - haven't got it -"
Captain: "There it is."
Flight Engineer: "I guess it does."
Captain: "Yeah, I guess it does - right on the nose."
[At the instant he says the word "nose" there is the sound of
the number 3 engine exploding followed by ratcheting sounds.]
Captain: "[expletive deleted] what was that?"
By playing with the autothrottle controls - in what amounted to an
in-flight failure-analysis test of the autothrottle system - the crew
managed to produce a condition where the engines were pushed to higher
rotation speeds than they were designed for. According to audio analysis
of the CVR tape, all three engines surged (#1 to 105%, #2 to 107% and
number 3, which failed, to 110%).
Pieces of the engine fanblades struck the fuselage breaking a window
near seat 17H. According to a witness, the occupant of the seat was
partially forced through the window opening and was temporarily retained
in this position by his seatbelt. Efforts to pull the passenger back into
the airplane by another passenger were unsuccessful, and the occupant of
seat 17H was subsequently forced entirely through the cabin window.
The New Mexico State Police and local organizations searched
extensively for the missing passenger. A computer analysis was made of the
possible falling trajectories, which narrowed the search pattern. However,
the search effort was unsuccessful, and the body of the passenger was not
The plane made an emergency landing at Albuquerque International
Airport. It was repaired and was later flown by Pan
Am (as Clipper Meteor) through 1984. It was scrapped in
A picture of this aircraft is here.
Source: Adapted from National Transportation Safety Board (NTSB)