Structural Breakup of Commerical Aircraft



This paper puts forward some of the issues relating to the structural breakup of commerical aircraft when involved in ground collisions, in what can be termed "controlled flight into terrain" where the pilots may have some control or, where the aircraft impacts at reduced speed. In particular during the take-off, approach and landing phases.

In specific circumstances aircraft would appear to have fractured in similar places at a position, between the wings' leading edge and the rear of the flight cabin, and/or, between the wings trailing edge and the forward edge of the tailplane.

This research project aims to collate information from various incidents which display similar characteristics in order to make a comparison of the data.

Studies have been made of detailed reports, by the Air Accidents Investigation Branch; United Kingdom, as part of the investigation into the Kegworth accident (8th January 1989). Attention is drawn to this study in the Accident report section 1.17.17 "Other survivable accidents" where it states:

"...reports from a number of accidents which had occurred to narrow-body jet transport
aircraft in the USA and Canada between 1972 and 1988. The 13 accidents selected all
involved narrow-body aircraft and at least a partially survivable impact; 5 occurred
during the take-off phase, 6 during the approach and landing phase and 2 were
power-off forced landings. 

On comparing these accidents with G-OBME, it was apparent that the structural disruption 
to G-OBME was characteristic of other off-airfield accidents which had involved landing 
undershoots, failed go-arounds and power-off forced landings; accidents involving 
rejected take-offs and landing over-runs were generally less severe. Two recurrent 
features of these accidents were the major disruption which had been caused by an 
impact after the initial ground impact, and the occurrence of 2 major fuselage 
failures, one forward and one aft of the wing." 


The following photographs illustrate this type of structure failure as a result of a ground collision.

[Photograph] Date: 25th January 1990
Location: New York, USA
Carrier: Avianca
Aircraft: B-707-321B
Registration: HK-2016
Flight No: 052
Passengers and Crew: 158
Fatalities: 73
Phase of flight: Decent
Reason for crash: Ran out of fuel





Report: Click Here


[Photograph] Date: 8th January 1989
Location: East Midlands, UK
Carrier: British Midland
Aircraft: B-737
Registration: G-OBME
Flight No: BD092
Passengers and Crew: 126
Fatalities: 47
Phase of flight: Climbing
Reason for crash: Improper engine shutdown














Report: Click Here
Survivors Seating location Plan, and other information: Click here


[Photograph] Date: 20th November 1974
Location: Nairobi, Kenya
Carrier: Lufthansa
Aircraft: B-747-130
Registration: D-ABYB
Flight No: LH 540/19
Passengers and Crew: 157
Fatalities: 59
Phase of flight: Take-off
Reason for crash: Leading edge flaps retracted

Report: Click Here
Survivors Seating location Plan, and other information: Click Here


[Photograph] Date: 18th June 1972
Location: Stanes, UK
Carrier: BEA
Aircraft: HS 21
Registration: G-ARPI
Flight No: 548
Passengers and Crew: 118
Fatalities: 118
Phase of flight: Climbing after take-off
Reason for crash: Deep Stall




Report: Click Here


[Photograph] Date: 20th September 1989
Location: New York, USA
Carrier: USAir
Aircraft: 737-400
Registration: N416US
Flight No: -
Passengers and Crew: 63
Fatalities: 2
Phase of flight: Take-off
Reason for crash: Rejected takeoff

Report: Click Here


[Photograph] Date: 31st August 1988
Location: Dallas, USA
Carrier: Delta Air
Aircraft: B-727
Registration: N473DA
Flight No: 1141
Passengers and Crew: 108
Fatalities: 14
Phase of flight: Take-off
Reason for crash: Slats not properly configured


Report: Click Here


[Photograph] Date: 23rd January 1982
Location: Boston, USA
Carrier: World Airways
Aircraft: DC-10
Registration: N113WA
Flight No: 3011
Passengers and Crew: 212
Fatalities: 2
Phase of flight: Landing
Reason for crash: Ice on Runway
(This fuselage may have been cut)


Report: Click Here


[Photograph] Date: 8th May 1997
Location: Shenzhen, China
Carrier: China Southern Airlines
Aircraft: B-737-31B
Registration: B-2928
Flight No: CZ3456
Passengers and Crew: 74
Fatalities: 35
Phase of flight: Landing
Reason for crash: Bad Weather




Report: Click Here


Comparative Diagrams of Survivor Locations

This page is currently under construction as data is researched and plotted, the pages purpose is to enable survivor locations to be easly compared with overlays available.

Data comparison Click Here



[Line Art] It is likely to be the case that these structural breakups have resulted from the aircraft impacting the ground from a similar attitude. It is often the case that the aircraft strikes the ground twice in these circumstances. The tail section impacting on the first strike followed by the airplane landing on its underside.




In each case the middle section of the aircraft over the wings has remained relatively intact. It is also the case that passengers seated at the extreme rear and extreme front of the aircraft along with the flight crew may survive such an incident.

Risk Factors

Statistics now show that during the past five years from 1991 the most dangerous phase of an aircrafts flight is the approach. Statistical trends now show that the phase of flight in which most accidents occur has changed during the period 1951-1995. Overall during the period 1951-1995 the en-route phase is the most dangerous, however when looking at the change in trends over the periods 1951/70, 1971/80 and 1981/95 the approach phase is now seen to be the most critical followed by climbing and takeoff. Click Here for Graphs showing 1951/95 and 1990/95 statistics. Data obtained from "Airlife's Register of Aircraft Accidents" page 363/5 - by Antonio Bordoni (1997)


It is also notable that 80% of all accidents occur within 1Km of an airport.
"Four fifths of all accidents involving passenger planes occur
within a single kilometre of an airport, so firefighting teams
should (and generally are), be on hand within a few minutes.
As a result, 95 per cent of passengers survive a crash if there
is no fire. If there is only a third come out alive."

"Black Box" page 68, by Nicholas Faith (1996)


Take-off and Landing

During the take-off and landing phases, involving passenger aircraft, aircraft are travelling at lower speeds thus reducing the force of any ground impact on passengers and increasing the chance of survival.

It is important to note that overall flying is one of the safest means of travel, the train being the safest followed by bus and aircraft. Even during the takeoff or landing phase the odds of being killed are calculated a being 3 in 1,000,000.

In light of these statistics where might it be safest to sit during a flight in order to improve your chances of survival should the aircraft crash in the take-off or landing phase?

Considerations

The following points are amonst those requiring consideration.

1.  Approach climbing and take-off are the most critical aspects of the flight
    at odds of 3 in 1,000,000 as to being killed.

2.  Four fifths of all accidents occur within 1Km of an airport.

3.  Controlled flight into terrain, with reduced impact force may increase
    surviveability.

4.  Similarities in the pattern of structural breakup on crashing.

5.  Structural integrity of the airframe, the area above the wing is quite strong
    as it has to support the weight of the aircraft in flight.

6.  The location of emergency exits.

Taking these various factors into account along with the odds of a crash occuring during the most critical phases of the flight it has been suggested that the safest place to survive such and incident is directly over the wing within 2-3 seats of an over wing emergency exit.

This research project aims to collate information from various incidents which display similar characteristics in order to compare data.

Most of the survivors on the 20th November 1974, Nairobi, Kenya disaster were seated either over or just forward of the wing section. The page showing the seating location of the survivors on this flight is located at the crash photograph section. Data is also being collected on the 8th January 1989, British Midland disaster in relation to survivor seat location. Any additional information on passenger location concerning these and the other flights listed would be welcome. Forward to Liskd.SkyNet@dnet.co.uk

Whilst it may be the case that any seat on an aircraft is as safe as any other it may be the case that during the more critical take-off, approach and landing phases seat location may be a factor in survivability, it is certainly an area where more data could be assembled and further research carried out.

This paper is a discussion document and was written as a result of encountering a number of photographs of commerical aircraft, of different makes and types, which had fractured upon impact showing similar damage patterns. Damage was sustained mainly during take-off, approach or landing phases.


It should be understood that air disasters are usually the result of a complex chain of events rather that a single cause.

It is through the efforts of Air Accident Investigators throughout the world that problems are identified, solved and recommendations made to improve safety.



By David Lisk
Liskd.SkyNet@dnet.co.uk
Disclaimer: While every effort is made to ensure accuracy, no representation is made as to the accuracy of, and no acceptance or any legal responsibility is taken for any errors, ommissions, mis-statements or mistakes within the pages of this web site or on other web sites which may be linked to this site from time to time.