WW2 altimeter settings

ME543, thank you for the correction, it was from memory as I didn’t have the book to hand. I have now.

His narrative style is novelistic rather than chronological. Rather than take us through one mission from preping the aircraft, mission planning, kitting up, pre-flight etc etc he feed small pieces of information that eventually build up to a big picture. He does not tie any raid to a date so it is not possible to say with any certainty to which Berlin raid his narrative refers.

I will give a flavour of his style as he leads us to the Berlin raid.

“Operation postponed!”
. . .
“For two hours – wait in the mess.”

By the time we reached the mess, it was fully dark and raining heavily. The crews had taken off their flying clothing and were lolling in chairs like men reprieved. We had been told to return to the crew room at 9 o’clcok, but at 7.30 the tannoy demanded we report immediately.

. . .

“A scrub?”

“Command is determined that you’ll go.”

. . .

The forecast was gloomy in the extreme: cloud heaped on cloud to 15,000 feet: a front across the North Sea; a low icing level.

. . .

The wing commander said “You must leave immediately. Navigators can complete their flight plans in the aircraft.”

. . .

Soon after the engines started I felt a prod from Graham. “here’s the 500.” He thrust a grimy file of papers into my hand to be passed to Geoff. A moment later they came back with G Maddern pencilled in the usual place, indcating his acceptance of the aircraft.

[This is the first time he has mentioned an aircraft being signed for.]

. . .

When I plugged in my headphones I heard the vpoice of the duty controller. this was unusual, as we were observing radio silence.

“All aircraft standby! The flarepath is changing to runway zero six.”

“Hell, there’ll be some fun now!”

In a few moments an aircraft broke silence.

“Control from H Harry, permission to switch off – my engines are overheating.”

There were sharp exchanges with control, then the pilot’s abrupt decision, “H Harry – I’m switching off.”

Other aircraft began reporting the same difficulty, but the more experienced men were silent. On other aerodromes the same trouble was being reported. A wind change along the east coast had necessitated the change in direction of take-off. In many case whole lines of ‘planes standing nose to tail had to turn about in the darkness. On one squadron this resulted in such chaos that the operation was cancelled; on another, only three got away. At Elsham we were more fortunate, only two crews failing to take off.

At 0040 Berlin filled the southern horizon.

“Not as bad as the Valley,” remarked Doug drily, “Not as concentrated.”

“I don’t need it no more damn’ concentrated than that!”

“How long before we bomb, navigator?”

“Three minutes.”

“Funny; it seems quiet.”

We continued towards the target, but although we reached the edge of the search light belt the city remained unmolested.

“Did you check your watch, navigator?”

“At final briefing – so did you.”

“Well, I make it forty-two and the attack was supposed to start at thrity-eight.”

“Forty-two is right. Probably the Pathfinders have boobed.”

“We’ll wait out here until something happens.”

For 15 minutes we circled Berlin. We did not know then that the attack had been put back 15 minutes; somehow the message had never reached us. For those 15 minutes 103 Sqn had Berlinto themselves. At fifty-four a Pathfinder marker was laid. A Lancaster dived on it and the attack began.

We heard the next morning that double the weight of bombs had been dropped as on the worst raid of the London blitz. Thirty-three aircraft were missing.

~~~~~~~~~~~~~~~~~~~~~~

That was the whole story of that raid. I would suggest that “A Lancaster dived on it” was not actually a dive in a sense of changin height but a ‘dive’ as in ‘pounce’, grab or get in quick.

Fifteen minutes just stooging around – balls the size of cannon balls.

No Moon Tonight

Hi Brian,
Please note the author of “No Moon Tonight” is Don Charlwood (not Charnwood); his excellent book covers his tour of operations as a navigator in 103 Squadron in 1943, he was tour-expired by 1944.
Regards
Max

Thank you PN. I thought my original question was so simple it would be answered quickly; unfortunately I’m still in the dark. I suppose that provided an aircraft was within +/- 300 ft of its allotted height, it mattered not if the was based on QFE or QNH at take-off – provided all aircraft were using the same type of setting and flying in the same direction. Something tells me there were other things more important than H&S in those days.

As a matter of interest does Charnwood’s book make any reference to the Berlin raid on 24/25 Mar 1944? If so does he mention wind speeds?

Brian

No Moon Tonight

I have just finished Don Charnwood’s book. It was written in a novelistic style but is actually a contemprary non-fiction account of his time in Bomber Command. It had some interesting snippets that illuminate some of the points mentioned above.

The sqn would take-off in stream from Elsham Wold and depart to the north before climbing to altitude and assembling over the airfield. The sqn would then set heading for the Norfolk Coast at 15000 feet.

While they had assigned bombing altitudes they often had to fly at different levels for fighter evasion. He records several instances of crews being bombed by aircraft above them.

He mentions two landfall points: Mablethorpe and Dungeness. From there he would navigate to Elsham. On contacting Elsham the reply was “B – Beer Pancake Pancake QFE one zero zero fife”

On wind finding he clearly relied on GEE. On one occasion the pilot mis-set the compass by 10 degrees when they were recovering via France and Dungeness. Don was unable to get a fix and check wind because of heavy Gee jamming. When he did get a fix they found they were on track because of an unforecast change of wind.

On another occasion they jettisoned their 4000lb cookie when attacked by a fighter and then pressed on with just incendiaries.

So at least we now know they used QFE for landing.

This looks as though this is going to be one of the unanswered questions. The RAF Museum has replied to my request for help, but has been unable to provide a definitive answer.

My thanks to everyone for their help.

Lyffe, thanks for that. I have not ‘dated’ that part of the tale accurately but they had just converted from Halifax to Lancaster at Elsham Wold.

While the Research Branch (if they existed then) would have done much work a lot was also done on the sqns. I once found several pages of pencil notes working out bomb sight theory and sighting angle calculations. I passed them all to the RAF Museum as it was building up.

In answer to your question about updating of winds PN I can offer the following.

Without going into the whys and wherefores wind forecasting at the beginning of the war was very hit and miss, not only because there was no information over enemy territory, but also because the Met Office had never previously been required to produce such information to high accuracy – the expertise did not exist.

In Feb 1943 a special branch was established at the Met Office HQ (not Bomber Command), tasked with forecasting winds on a more scientific basis. Although the crews would undoubtedly say otherwise there was an improvement in the forecasts, but forecasters were still hampered by a lack of information from Germany. Although the German meteorological code had been broken, it kept being changed which meant there were still periods when no data were available.

By the end of 1943 all crews conducted their flight planning using the forecast winds prepared by Met HQ, but about 20 of the aircraft at the front of a bomber stream were nominated as ‘wind finders’, measuring the winds over predetermined legs. These ‘found winds’ were transmitted back to Met HQ where they were compared with those forecast and, if differing greatly revised winds were broadcast to the bomber stream – thus those at the back of the stream were flying on more accurate data than those at the front – at least that was the theory. It didn’t always work (as on the Night of the Big Wind), but it certainly helped.

So yes, revised winds were issued.

Unfortunately it would not have benefited your Oboe aircraft as it was in front of the stream. In this case the Nav would have to compare his ‘found’ wind with the forecast issued and use his experience to adjust the track accordingly.

They also did not seem to use minimum safety altitudes either,so many were lost descending through cloud into cumulus granitus.

Ah, that reminds me, Air Ministry Safety Height Procedures – the bicycle chain construction. It was really only useful in a slow moving aircraft as construction was not quick.

Anyone want me to try and repeat the procedure here?

I have a copy of a No 582 Squadron Lancaster daylight raid on Cologne on 23 Dec 1944. There is no mention of altimeter settings so it seems they flew on QFE only. This probably explains why so many collided with high ground. They also did not seem to use minimum safety altitudes either,so many were lost descending through cloud into cumulus granitus.

Broadening the altitimeter/altitude debate, I read an account in a book today by a navigator on one of the first Oboe raids. What he said was quite simple but that belied the complexity of the attack. He wrote the book in 1956.

We know that Oboe Mosquitos flew along an Oboe beam until a pre-calculated release point determined by a UK based ground station and that the bombers dropped on the ground or sky marker as appropriate.

But . . .

That Oboe release point had to be pre-caluclated based on forecast winds and the Mosquito had to fly at a given height and airspeed. The first question therefore was whether the wind was updated in flight.

In his book Charnwood said they were briefed to fly at 23000 feet twice their normal altitude and at a precise speed and direction. Now this is what he did not say.

A bomb trajectory is horizontal at release and given sufficient altitude nearer verticle at impact. It can be said to follow an increasingly steep curve. Naturally the direction of the bomb fall line is such that the bomb hits the target.

For sky marking however the situation becomes dynamic.

First the marker must be dropped at an offset distance, allowing for wind drift, such that a bomb dropped from a greater altitude will pass through the marker and continue to hit the target. It is bit like walking past a dartboard as someone passes a circular disk in front of you. Your dart must pass through that disk en route to the bull.

The boffins, of Bomber Command Research Branch were still at it when they calculated our nuclear weapons release procedures too. Their work was effective in WW2 and we had faith in them for WW3 as well.

As a wg cdr said when I was at the Bombing School – welcome to the best sport in the world – visual darts from a mile or more high.

At the time he was right, later I found a better game. Throwing darts at a target you can’t see, and I don’t mean by radar. Dropping a torpedo on an evading submarine, and getting a ‘kill’ is far better fun.

In WW2 the same ‘boxed’ secrecy would probably have prevailed with night fighter intruder sqns being told only minimal information about the bomber force attacks.

I now have the answer to the supplementary questions I asked about the briefing of Mosquito crews on intruder operations. My informant tells me that he recalls being fully briefed on the routes, timings and targets of the main force operations they were supporting. He also told me that the tactical brief they received varied considerably. On some occaisions they would be assigned to what could be compared to an escort role for the bomber stream, on others they might be tasked with interdicting specified night fighter airfields or sometimes given a free ranging role of operating up to 150 miles either side of the bomber tracks.

exmpa

My thanks Exmpa and Pontius Nav.

I never expected a simple answer to my query, as it was clear from the 16.12.48 ‘Flight’ article to which I referred in my opening post, that there did not appear to be any firm rules – perhaps this is why there were so many terrain collision accidents.

I’m still waiting for a response from Hendon, but I bet it’s not a question that has been asked before.

I have made a few enquiries and this is the reply via a third party:

My good friend in the village who flew Mosquitos during the war and with BOAC afterwards says:
We didn’t know of 1013. We set the altimeter to read
zero at take off. Flew on that same setting throughout the sortie until on
returning when we put on our IFF to speak to our Sector Controller, who
would, in turn, pass us over to our airfield controller who would pass us
the altimeter setting to set.

WRT PN’s comments above:

In WW2 the same ‘boxed’ secrecy would probably have prevailed with night fighter intruder sqns being told only minimal information about the bomber force attacks.

I have put some additional questions to the informant on that subject and hope to be able to provide further information.

exmpa

Bomber Command and the Groups

Digressing somewhat, but until its disbandment in 1968 Bomber Command was a complete entity within itself. As well as an Air Staff it also had a complete P-staff (personnel) function.

Aircrew were posted from Flying Training Command to Bomber Command by the Air Secretary’s Department. This posting to Bomber Command was for a period of 5 years or 2 tours. It could of course be extended for 5 year periods and most aircrew were on commissions for up to 16-20 years only.

Bomber Command handled its officers’ careers with only a few high fliers ‘retained’ by the Air Sec although even so inter-command postings were relatively rare.

Equally operation liasion between Commands was also a rarity. On one exercise Bomber Command had to hire in Dan Air and BUA as Transport Command would not accord them the necessary priority.

Also there was no liasion between Bomber Command and Fighter Command over V-Force routing and air defence of the UK, at least as far as either fighter or bomber crews were concerned and I suspect even at higher levels there was no coordination.

In WW2 the same ‘boxed’ secrecy would probably have prevailed with night fighter intruder sqns being told only minimal information about the bomber force attacks.

the Group HQs were themselves part of a chain, and their instructions/orders originated from HQ Bomber Command.

Your mention of pressure pattern flying and Coomand reminds me of a story, I don’t know whether it was a true story or an account but I have little doubt that there would have been an element of truth whatever.

The tale involved a Lancaster that returned to base early but without its bombs. IIRC it may also have suffered damage. There was an accusation of LMF and that the crew had simply left the bomber stream, jettisoned their bombs and returned home. I think this may have been before the target photographs were introduced.

The crew was grounded and the navigator sent to Command where he protested their innocence and said that they had lost so much fuel that they could not have flown the planned recovery route. He had got out the met sheets and realised that if they flew a longer track well to the north of the planned track they could fly around a low pressure area with a tail wind rather than the forecast headwind.

This they had done which both accounted for their early return and the fact that they had not enough fuel. Naturally, so the story went, this was seen as poppycock. However the CNO – the Command Navigation Officer was sufficiently intrigued that he called for the met forecasts for that night and reconstructed the mission. In his reworking he proved that indeed the navigator’s application of Buy Ballot’s Law would have enabled the crew to do what they claimed. The nav was exonerated and the crew reinstated.

My apologies for my delay in responding to the various points raised, but I’ve been away for a few days.

I don’t think we should be influenced too much by the references to Groups in autobiographies. These are written by men who were very young (and probably very junior) during the war, and were thus at the end of a long line of decisions. I have little doubt that briefing officers usually/often prefaced their briefings with ‘Group says …’ or something similar, but that would have been due to the teleprinter messages containing details of an operation originating from the Group HQ. However, the Group HQs were themselves part of a chain, and their instructions/orders originated from HQ Bomber Command.

At the start of the war there is no doubt that Group HQs were responsible of operations; the number of aircraft involved was usually small (often part squadron level)and, with raids being mostly conducted in daylight the Mark 1 eyeball was as good a way of avoiding collision as any other. When daylight losses proved the folly of daylight bombing operations were switched to night but, again, numbers of aircraft involved were small, and crews usually decided their own route and time frame.

Matters only changed when aircraft from more than one Group were involved in an operation – there had to be some co-ordination otherwise the aircraft from, say, two groups would be flying on different information (and I’m not just talking about heights). When Harris arrived at HQ Bomber Command matters really did change, and although the Groups were consulted, there had to be an over-riding authority to ensure that details were consistent.

I think the clue as to what pressure setting was used can be found in Met Office history. From Dec 1940 there were daily conferences between the Met Officers at the Groups and HQ; at first these only agreed a common forecast for the night’s weather, but the forecast winds remained the responsibility of the Group Met Officers. These were found to differ enormously between Groups, and in Feb 1943 a new system was introduced whereby upper air charts were drawn to a datum of 1013.2 mb, instead of sea level, and winds calculated from the patterns produced. Only the Met Office HQ had all the necessary information, and it was responsible for the forecasts. It was, in effect, the start of pressure pattern flying.

I suspect that for Bomber Command operations the 1013.2 mb pressure setting dates from this time, but flights below the transition level continued to use QFE.

That’s as I read it from research I’ve been doing on the met office at HQ Bomber Command (hence my lack of references) but I have asked the RAF Museum for its advice on the matter.

Further to the previous posts, I have found a book No Moon Tonight (1956) but reprinted more recently. The first raid covered was a Wellington raid on Bremen at 9000 feet.

This was based on a Group forecast that it would be below cloud (12500) above the light flak and below the heavy flak/fighters.

The point about pressure settings of course is that crews needed to know the height above ground rather than a standard setting as all the bombing calculations were based on true altitude.

The pressure setting at base would probably be as accurate a datum as any forecast over enemy territory.

Didn’t bomber crews ignore their assigned altitudes and simply fly as high as their bomber/payload would allow?

I would say that some did and some did not,I have read one autobio by a pilot years ago(sorry no diary,cant remember name) who did climb as high as poss.Some crews probably obeyed orders(esp inexperienced ones??) and others worked out their own survival strategy.

And moments later a second story from one of my nav instructors:

“No strong memories but I am pretty certain the Bomber Force used a standard altimeter setting of 1013.2 mb’s except for take off and landing when, in the local area, the QFF would have been set. I don’t recall a regional pressure setting system. QNH, I think, was introduced post war and sparked off the QFF v QNH debate (QFF = barometric pressure at a stated place reduced to mean sea level; QNH = the pressure setting that causes the altimeter to read the height above mean sea level of the touchdown on landing plus the height of the altimeter above the ground – AP3340). To use other than a standard pressure setting would have led to chaos!

On operations height and time separation were used to reduce the risk of collision. Heights to fly were planned at Group level and given to crews at briefing. They varied during a mission for tactical reasons. In my time, Oct 44 to May 45, maximum height was rarely used. A quick glance through some squadron operational records shows that bombing whilst on 106 Squadron (to Feb 45) was from as low as 4,500ft up to 21,000ft with around 12,000ft as most often.”

I got this question from a friend. I am seeking a definitive answer but first my own experience.

In the Varsity nav trainer the navigator’s altimeter did not have a sub scale setting. Instead it was set to zero on the ground and once we passed transition altitude we used a small knob to reset the altimeter to 1013. This was identified by a lubber line.

When we returned to base at the end of the sortie we left it on 1013. Naturally it would have been possible to reset to QFE by using pressure difference from 1013 times 30 but we were never taught that technique.

As for the earlier remark about resetting altimeters when crossing FIR boundaries, that is what you still do but for Regional Pressure Settings areas.

Now for some recollection from a WW2 navigator:

“Quick response from the top of my head. I did not keep a diary or make notes during the period or after, so it is a question of my general recollection which may be a little faulty after sixty-two years. I certainly always had a specific altitude specified at which the bombing run was to be made and always tried to accomplish a steady run-up and release at the given level regardless of the temptation at times to deviate. We took a string of photgraphs, of course, which recorded the altitude and heading throughout the run-up and release and after, and these could be seen on debriefing to assess the result of each aircraft’s attack.

I do not have any special memory of the altimeter settings used in the stream. Of course our attacks were organised by bomber groups, my group being 3 Group. Therefore our squadrons in a particular part of the stream would be based in a relatively small, flat part of the country and our altimeter settings would not affect our relative altitudes to any great amount whether set to show zero or height above MSL on landing at home base. Nor would the barometric pressure vary much in the groups base area at any given time. I think we probably were given a QFE to use when cleared for approach and landing on return to base.There are people who either remember events very well or did make notes at the time who have written fairly detailed account of squadron life who might be able to answer this question better than I can.”

So from this recollection groups of bombers may have been on the same pressure setting but different from other groups. As someone said, the return route was side stepped from the outbound. Furthermore it would have been plain stupid to fly on a fixed pressure setting like 1013 and at fixed levels as in the quadrantal system. Flying predetermined heights on the base or group setting on the other hand would have avoided confliction in the immediate target area.

As for flying as high as possible, this was covered in Bomber by Len Deighton with Alf Price as a researcher. Here, IIRC, some pilots would claw a few more feet altitude by dropping the flaps and jumping a couple of hundred feet at a time.