Date:	Friday 27 September 1946
Time:	17:40 LT
Type:	de Havilland DH.108 Swallow
Owner/operator:	de Havilland Aircraft Company
Registration:	TG306
MSN:	DH.108/02
Fatalities:	Fatalities: 1 / Occupants: 1
Aircraft damage:	Destroyed
Location:	Egypt Bay, Gravesend, Thames Estuary, Medway, Kent -   United Kingdom
Phase:	Manoeuvring (airshow, firefighting, ag.ops.)
Nature:	Test
Departure airport:	Hatfield Aerodrome, Hatfield, Hertfordshire (EGTH)
Destination airport:	Hatfield Aerodrome, Hatfield, Hertfordshire (EGTH)
Confidence Rating:	Information is only available from news, social media or unofficial sources

Narrative:
A test flight was being conducted to assess the controllability of the DH 108 at high speeds at low altitudes (5,000 feet) in preparation for an attempt at the world air speed record. It was decided to carry out a practice flight in preparation for an air speed record attempt later in the year. The area chosen was to be the Thames Estuary as test flying, being quite hazardous by its very nature, afforded a largely un-populated area should anything go amiss.

The Swallow, serial TG306, took off from Hatfield at 17:26 hours for a short test flight. The intentions were that De Havilland would do a shallow dive from 10,000 feet up to Mach 0.87, followed by a level speed test up to 650 mph. At 17:39 the aircraft was seen a few miles North East of Gravesend travelling towards Cliffe, and what a sight it must have been to onlookers: a futuristic design, glinting in the sunlight with the roar of its 3,300 lb thrust turbo-engine.

At 8,000 feet it powered towards the speed of sound when suddenly all was to go quiet: the Swallow had disintegrated and the wreckage fell into the mud at Egypt Bay in the Thames Estuary off Gravesend, Kent

Examination of the wreckage showed that the aircraft disintegrated due to down loads on the wings, with the starboard wing being the first component to fail. A report from the manufacturer's states:

"The results of the high-speed wind tunnel tests have shown that at high Mach numbers there is a loss of elevon effect in the pitching plane which later changes to a reversal of control: this is accompanied by a nose down change in trim, and reduced longitudinal stability. It is thought that these features probably are the basic cause of the accident since their combined effect could result in the aircraft nosing over into negative incidence without the possibility of recovery".

In all, three DH 108 Swallows were constructed, and all three eventually claimed the lives of their pilots. The wreckage of DH.108 TG306 was recovered on 28 September 1946, the day after the accident. However, Geoffrey De Havilland's body was not recovered until it was washed ashore at Whitstable on 7th October 1946.

When Geoffrey De Havilland's body was found on the mud flats at Whitstable, his parachute pull ring was untouched; he had suffered a broken neck, the result of the aircraft having undergone severe and violent longitudinal oscillations prior to break-up, which caused de Havilland's head to strike the cockpit canopy with great force. (The implication being the Geofrey De Havilland Jr died of a broken neck and not as a result of the DH.108's break up in flight).

Another pilot who flew the DH 108, Capt. Eric "Winkle" Brown, suggested that a factor in de Havilland's death was his height (de Havilland was over 6 ft tall); Brown suffered similar oscillations during a test flight but, because of his shorter stature, they did not cause his head to contact the cockpit hood.

The 1952 David Lean film "The Sound Barrier" refers to this event. Geoffrey de Havilland Jr was succeeded as De Havilland's Chief Test Pilot by John Cunningham.

1. Watkins, David. De Havilland Vampire: The Complete History. Thrupp, Stroud, UK: Budding Books, 1996. ISBN 1-84015-023-8.
2. Inquest into pilots' death: Evening Telegraph - Wednesday 9 October 1946
3. Report into pilots' funeral: Northern Whig - Friday 11 October 1946
4. Flight Magazine, October 3rd 1946: https://www.flightglobal.com/pdfarchive/view/1946/1946%20-%201978.html
5. http://sussexhistoryforum.co.uk/index.php?topic=872.0
6. https://en.wikipedia.org/wiki/De_Havilland_DH_108
7. https://www.findagrave.com/page=gr&GRid=47425924
8. http://www.unrealaircraft.com/wings/dh108.php
9. http://www.kenthistoryforum.co.uk/index.php?topic=15542.0
10. http://www.cliffehistory.co.uk/swallow_disaster.html
11. https://en.wikipedia.org/wiki/Geoffrey_de_Havilland_Jr.#Test_pilot
12. https://www.flightglobal.com/pdfarchive/view/1946/1946%20-%200770.html
13. National Archives (PRO Kew) File AVIA 5/28/W2366: https://discovery.nationalarchives.gov.uk/details/r/C6578212
14. National Archives (PRO Kew) File BT 217/876: https://discovery.nationalarchives.gov.uk/details/r/C575030
15. https://en.wikipedia.org/wiki/Hoo_Peninsula#The_marshes

Date/time	Contributor	Updates
25-May-2010 00:35	angels one five	Added
26-Apr-2013 02:56	Dr. John Smith	Updated [Registration, Departure airport, Destination airport, Source, Embed code, Narrative]
26-Apr-2013 03:02	Dr. John Smith	Updated [Source, Embed code]
18-Dec-2014 10:25	angels one five	Updated [Time, Aircraft type, Operator, Location]
29-Dec-2018 20:13	TB	Updated [Time, Aircraft type, Cn, Embed code]
17-Nov-2019 02:50	Dr. John Smith	Updated [Time, Location, Departure airport, Destination airport, Source, Embed code, Narrative]
18-Nov-2019 00:40	Dr. John Smith	Updated [Location, Source, Narrative]
18-Nov-2019 00:42	Dr. John Smith	Updated [Narrative]
24-Nov-2019 00:31	Dr. John Smith	Updated [Source, Narrative]
12-Dec-2019 16:51	Dr. John Smith	Updated [Source]
17-Feb-2020 22:32	Dr. John Smith	Updated [Source]
31-May-2023 19:01	Dr. John Smith	Updated [[Source]]