1956 — April 1, TWA Flight 400 crash after takeoff from Greater Pittsburgh AP, PA — 22

— 22 AirDisaster.com. Accident Database. Accident Synopsis 04011956.
— 22 Aviation Safety Network. Accident Description. Trans World Airlines, 01 Apr 1956.
— 22 CAB. AIR. Trans World Airlines, Inc., Martin 404, Near Greater Pittsburgh…Apr 1956.
— 22 NFPA. “Large Loss Aircraft Fires of 1956.” Quarterly, Vol. 50, No. 4, April 1957, p. 318.

Narrative Information

Civil Aeronautics Board: “Trans World Airlines Flight 400 of April 1, 1956, a Martin 404, N 40403, crashed and burned immediately following takeoff from the Greater Pittsburgh Airport… about 19:20. The hostess and 21 of the 33 passengers were killed; both pilots survived. The aircraft was destroyed by impact and fire….

“Flight 400 was regularly scheduled between Pittsburgh, Pennsylvania, and Newark, New Jersey, with stops at Harrisburg. Reading. And Allentown, Pennsylvania…..

“Takeoff clearance was requested and granted at 1919. About one minute later tower personnel observed a seemingly normal takeoff and initial climb immediately followed by a left turning descent, crash, and erupting fire just beyond the southwest boundary of the airport.

“Passengers extricated themselves from the jumbled wreckage through and ahead of the fire as best they could; some helped others while a few found themselves thrown out through tears and rents in the shattered fuselage. Although airport based fire-fighting equipment was dispatched with no loss of tune some 20 minutes elapsed before it reached the site because of the necessity of traversing circuitous country lanes. Once there, the conflagration, which by that time had nearly consumed the wreckage, was quickly smothered….

“After becoming airborne, a sharp yaw to the left was experienced at the time of the first power reduction by the first officer. Almost simultaneously he saw the left engine No. 1 zone fire warning light flash on and off and then stay on. He did not hear a fire warning bell. Captain McQuade, on the right, was performing the duties of the first officer. Captain McQuade stated that at the time he had operated the gear up handle and was toggling the r. p. m. to the proper engine speed following the first power reduction. The captain, at the time of feeling the aircraft yaw left, did not see the zone 1 fire warning light nor hear an alarm. However, he did observe a rapid drop in the left BMEP gauge, which went to zero, and reached under the right arm of the first officer, then on the throttles, to retard the left engine mixture control to idle cutoff which action is item No. 2 on the emergency checklist under the heading “Power Plant Fire-Failure.” The first officer stated that he then removed his right hand from the throttles and reached for the manual feathering button, whereupon the captain informed him that the automatic feathering device would cause the propeller to feather. Jesperson then, without actuating the feathering button, placed his right hand on the control column and reached forward with his left hand for the zone 2 firewall shutoff lever. The aircraft continued to yaw to the left and stayed sharply banked to the left despite attempted strong corrective control. At about that time the left wing struck the ground and the crash resulted. The maximum altitude reached from takeoff to impact was variously estimated as in the neighborhood of 100 feet; the total elapsed time was about 40 seconds, of which about 25 seconds were used in the takeoff roll. The time interval from the start of the difficulty to the crash was only approximately 10 seconds….

“An attempt to reconstruct the flight from the testimony of witnesses leads to the belief that the aircraft banked to a near 45-degree position prior to ground contact and that recovery from the bank and turn was under way at impact….

“Testimony indicated that the Martin 404 aircraft with a gross load similar to that of the aircraft involved, with landing gear extended, with takeoff flaps, and with a windmilling propeller, has a negative rate of climb.

“Analysis: It is not possible to determine just when the…exhaust connector clamp failed. It is possible that this clamp, whether it was the old cracked one or a replacement, could have failed during the flight from Newark on the day of the accident and have shifted so that daring the takeoff at Pittsburgh the collector ring mating connections separated just enough for escaping exhaust to impinge on the Fenwal unit scoop, deposit the observed soot, and signal a fire warning. It has happened on other occasions at this particular location. Presumably, the clamp was replaced at the time of the second prior 100-hour inspection and the replacement was found satisfactory at the time of the last 100-hour inspection. The subject clamp has been a troublesome and costly maintenance item and the carrier has changed designs several times. Currently the carrier is conducting service tests on a new type in its continuing efforts to find a satisfactory clamp. As a result of this accident, the Board recommended more frequent inspections of the exhaust system and the carrier has agreed to do so…

“First Officer Jesperson [who was piloting the takeoff] saw the fire warning light flicker. He either reduced the left throttle in compliance with the first item on the Martin 404 cockpit checklist under the heading “Power Plant Fire-Failure” or he diverted his attention from throttle movement to the fire warning light and inadvertently pulled the throttle sufficiently rearward to unarm the auto-feathering. Because he testified that he did not recall moving the throttle rearward it seems more than likely that he did so intuitively when his attention was diverted by the fire warning light.

“Captain McQuade on the right did not see the zone 1 fire warning light and only noted the BMEP gauge indicate power loss (which in all probability was the result of Jesperson’s retarding the left throttle). McQuade pulled the mixture to idle cutoff. The throttle having been retarded did not allow automatic feathering, only windmilling, thus setting up excessive drag and yaw to the left.

“Since Captain McQuade attempted to obtain auto-feathering by pulling back the mixture lever, it is apparent that he neither knew the left throttle had been retarded to a point where auto-feathering was inoperative nor did he expect this action by the first officer, despite such action being called for in the company’s emergency checklist for “Power Plant Fire-Failure.”

“In reference to the landing gear handle being found up, the captain may have raised the landing gear handle out of neutral position but not sufficiently upward to open the hydraulic valve for gear-up operation. The gear-up action probably was interrupted by the captain directing his attention to the drop in BMEP and the yaw. This would account for the landing gear being found in the dawn position at the time of impact. There appears to be no explanation of why Captain McQuade did not see the fire warning light.

“Testimony of TWA’s chief pilot for the Atlantic Region was that under similar circumstances he would not, as his first act, have pulled the left throttle back to the point where it disarmed the auto-feathering feature. He felt that the wisest procedure under these critical circumstances would have been temporarily to ignore the fire warning (particularly as it was a zone 1 warning) until enough altitude and speed were obtained to ensure single-engine flight. This opinion was shared by Captain McQuade. However, an emergency checklist had been provided to apply in the event of either a zone 1 fire or loss of power. The first officer started execution of this checklist but as he was reaching to feather the propeller manually, the captain interrupted his action. Believing that auto-feathering would take place. It is logically concluded that had the first officer continued as prescribed, the left propeller would have feathered. The complexity of modern aircraft and coordinated efforts required by multiple crews in an emergency dictate that all procedures must be carried out in strict conformity to prescribed checklists.

“The Board must conclude that each pilot reacted to the emergency as he understood the emergency but, as the two pilots had not full common knowledge of what was happening nor precisely what the other was doing, the resulting joint and uncoordinated actions resulted in a windmilling propeller making the aircraft unflyable under the circumstances.

“To minimize the possibility of any recurrence of this nature the carrier, after the accident, modified its emergency procedures for powerplant fire or failure. These revised procedures specify that the crew member who first observes the difficulty shall call out the emergency so that the captain can initiate immediate coordinated action by the crew. After it has been determined which engine has the fire or failure, the propeller is to be manually feathered before the throttle is closed or the mixture is cut. If the emergency occurs during takeoff and auto-feathering has not taken place by the time proper determination of the malfunctioning engine has been made, the propeller is to be feathered manually by pushing the feathering button…..

“Findings….

• At the time of the first power reduction the first officer saw the left engine zone 1 fire warning light come on and retarded the left throttle to a point where auto-feathering was deactivated.

• The first officer then reached for the left manual feathering button but was dissuaded from using it by the captain, who, not knowing that the auto-feathering was inoperative, attempted futilely to obtain it by pulling back the left mixture to idle cutoff.

• This action did not comply with the emergency procedures prescribed by the carrier for powerplant fire or failure.

• Although these were not the most desirable procedures, compliance without delay would have feathered the left propeller.

• The windmilling left propeller, the extended landing gear, and the takeoff flaps produced sufficient drag to make the airplane lose altitude and strike the ground.

• The cause of the fire warning was a failed exhaust connector clamp in the left engine which triggered an adjacent fire detecting unit.

• “After the accident the carrier revised its emergency procedures for power plant fire or failure.

“The Board determines that the probable cause of this accident was uncoordinated emergency action in the very short time available to the crew, which produced an airplane configuration with unsurmountable drag.” (CAB. AIR. Trans World Airlines, Inc., Martin 404, Near Greater Pittsburgh…Apr 1956.)

Sources

AirDisaster.com. Accident Database. Accident Synopsis 04011956. Accessed at: http://www.airdisaster.com/cgi-bin/view_details.cgi?date=04011956&reg=N40403&airline=Trans+World+Airlines

Aviation Safety Network. Accident Description. Trans World Airlines, 01 Apr 1956. Accessed 2/22/2009 at: http://aviation-safety.net/database/record.php?id=19560401-0

Civil Aeronautics Board. Accident Investigation Report. Trans World Airlines, Inc., Martin 404, Near Greater Pittsburgh, Pennsylvania, April 1, 1956. Wash., DC: CAB, Sep 14, 1956, 9 p. At: http://dotlibrary1.specialcollection.net/scripts/ws.dll?file&fn=8&name=*P%3A%5CDOT%5Cairplane%20accidents%5Cwebsearch%5C040156.pdf

National Fire Protection Association. “Large Loss Aircraft Fires of 1956.” Quarterly, Vol. 50, No. 4, April 1957. Boston, MA.