Thursday, November 16, 2017


One thought for the yellow dot on the pilot’s seat is it is a warning that the plate is made of armor steel, and therefore is much heavier than it might appear, so don't try to lift it/remove it without appropriate lifting equipment.

The other thought is that it is Gas warning paint was external: initially yellow and applied as a diamond shape visible to the pilot, but apparently later produced in the camouflage colors.
Sadly, as time moves on this bit of odd history is becoming. A point that nobody knows for certain what the painted yellow circle is for?

I've seen any photos of the "anti-gas" circle painted on the nose area of a Lancaster Bomber, supposedly just aft of the front turret, the accompanying text saying something along the lines of the use of such markings being withdrawn.

Gas indication panels on aircraft were NEVER intended to be viewed (for gas indication purposes) by personnel whilst the aircraft was in the air! I have read the official WW2 RAF Gas Manual and it is quite clear that the "powers that be" did due to WW1 expected gas attacks on RAF aerodromes as a matter of course (although apparently the Luftwaffe probably did not know about this!) and that dispersed aircraft were as good an article to apply the special paint to as anything else for the protection of personnel at these dispersed sites. Let's face it, do you recall ever hearing that anybody ever envisaged trying to bring down enemy aircraft in flight by extension of gas warfare up to 15 - 20,00 feet altitude??

Possibly not, for the reasons described. However, they would be needed to be visible by the crew for the case of arriving at an airfield which had been gas attacked, or for the knowledge that they had flown though a gas cloud and thus contaminated the aircraft with nerve agents as Germany had tons of Sarin gas but for some unknown reason never used it? Remember that in 1940 the RAF were planning to use gas on any invasion beach.

On a Spitfire and other fighters, they these gas, gas, gas markings were on the inner wing, near the trailing edge. It was approximately 18 inches square, normally painted, but could be thick paper, taped into position with the predecessor of 'Gaffer' or 'Duct' tape, normally colored black. The position on the Spitfire was 6 feet six inches from the center line of the fuselage, at the rear of the center line of the wing chord. On the Hurricane, the position was similar, but 9 feet 6 inches from the fuselage center line.

Little information exists as to how often it was changed or replaced, if at all, and it wasn't always present on all aircraft of the period, and removed, or painted over, if the aircraft was returned to a MU for deep service and re-paint.

The color was pale yellow, with a very slight green tinge, which changed color in the presence of various poisonous gasses, the color change hue depending on the type of gas.
By late summer 1940, with the threat of gas attack apparently diminished, these patches were seen less and less, eventually falling out of use, although, as stated in my reply, gas warning panels remained in use on military bases, and around Government and 'official' buildings in the UK throughout WW2, with the carrying of gas masks was obligatory.

Then again if It was not for the detection of poison gas the yellow indicates armor plating? As there is a lot of armor plate in the Lancaster. With every recovery many thick armor plates are found.
I also one read that a former crew member said that by marking the armor plating with a yellow disk, this would also make it easier to allow for any compass deviation corrections to be made.

So, the yellow dot on the Lancaster pilot's sliding head armour being an example. I've read all sorts of explanations (which side was hardened, something to do with magnetic fields/compasses to name a couple) but never that it was for gas detection. The Mosquito armor was similarly marked, and both continued to be so long after gas detection patches/paint were abandoned.

In November 1940 there was a short-lived modification to the Spitfire (cancelled after nine days), "to paint yellow markings on magnetic armor plates." It was abandoned because the armor was found not to affect the compass. This lends some credence to the magnetic field/compass theory.

The external patches were to indicate the need to decontaminate the aircraft (if exposed), which apparently involved washing with water. This was to protect the ground personnel from contamination. Having the paint inside the aircraft seems illogical.

Lancaster squadrons which eventually formed part of 100 Group carried a disc of gas detection paint on the outside nose, beneath the turret. This apparently was paint as I've read in the past by former ground and air crew from one of the squadrons, and of course served the same purpose as those patches on other aircraft types.

The same flight crew member in my readings said; that the disc on the head armor was for the detection of carbon monoxide inside the cabin, which could possibly leak from the heating system, driven off the engine exhaust, which fed into the cabin at the wireless op's position. This may or may not be the case, but I'll admit that the carbon monoxide detection 'badge' in light aircraft I've read that flew was more of a pink, rather than yellow color.
Though strange how the Avro Manchester didn't have the painted yellow spot but was the exact same seat & armor used in the Lancaster.

F.Y.I. Head armor material specification: 9mm armor plate (non-magnetic) indicate that it does not interfere with compass.
Of the 125,000 men volunteered to fight for RAF Bomber Command during World War II. 55,573 never returned, 10,000 were Canadian.
Richard Abbenbroek

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