The trouble was that this snag was so easy to fix. Off with the cursors onto the bench, out with a half-round file. File a "deckel-edge" along both sides of the cursors. Now you
can't confuse it with the central line. The "mod" was so quick and easy that no one saw any need to put it up for official adoption.
The word quickly got round all the MPN-1s in the RAF and you just did it. After the Sleap GCA School, which first recognised the fault, the two MPN-1s I later worked (Strubby and Gatow) had this "mod" done before I got to them. But there was an MPN-1 which (
AFAIK) hadn't. And I believe it wasn't a "Bendix", but was from another maker, but exactly to the same pattern.
This was the one at Heathrow. They had ILS, of course, and I would think that 99% of their traffic preferred this. Not that their GCA was idle, far from it. It was used (on the "belt and braces" principle) to monitor the ILS approaches. If the approaching aircraft were coming in too far adrift, they'd give Approach a shout. They'd done thousands of such "dry runs" over the years this way, but relatively few "real" ones. And their cursors had not been "modded".
I do not know why this was so. Their GCA was operated by the MCA, or the MoA or the BoT, or whatever. Either the RAF had not told them about this, or they had pigeonholed the advice (as being Not Invented Here ?). Our gremlin waited.....
One Day.
The day came on 1st October, 1956. The Vulcan which had been out to NZ and back on a flag-waving mission had behaved perfectly; our friends had been heartened and our foes dismayed. It was returning home now in a blaze of glory. The co-pilot was Air Marshal Sir Harry Broadhurst, newly appointed CinC of Bomber Command.
Mindful of the enormous cost of the new Vulcans to the hard-pressed taxpayer, he had recently issued a
fiat:
"There are to be no more flying accidents in Bomber Command". A poster was issued round his Stations to that effect (this I would not believe until I saw one).
"Ah, luckless speech and bootless boast
For which he paid full dear". (Cowper: John Gilpin's Ride)
The original plan had been that it should return without fuss to Lyneham. You never know, it might have disgraced itself, and be coming home under a cloud. But now all doubts were stilled, here was a fine photo opportuity for the Government to seize. It would come in to Heathrow and get the full red-carpet treatment, and be welcomed by the Great and the Good. All the freeworld's air attachés, their Press and cameramen were invited; this triumph of British aeronautical engineering would be displayed for all to see.
The Vulcan had ILS, of course, but this had to be re-tuned to each of the airfield's ILS it might need to use en route. This was then not a matter of merely punching a button or twiddling a knob. Separate discrete crystals had to be manually fitted at every stage. Of course, they had set out with a full kit of crystals for all the airfields on their itinerary, plus likely diversions. But it had never planned to use Heathrow: they didn't have the crystals for that, and for some reason (short of time ?) they couldn't get them now.
No problem, we'll use the GCA if the weather's bad. And it was, and they did.
Google will tell you what happened.
("Vulcan Crash Heathrow" will start you: there is interesting meat in all the links in the list, but I found it helpful to start with:
"VULCAN AIRCRAFT CRASH (REPORT) - Hansard 1803-2005").
and read in conjunction with my previous Post #4126 p.207, in particular:
("he will touch down among the approach lights about a half-mile short of the
threshold. And no one can work out why").
Post mortem and wrap-up and my comments (for what they're worth) next time,
Cheerio to all,
Danny42C.
...........the horse was lost