Джеймс Блатч - The Final Flight

A flicker of recognition passed across his face. “Ah, yes. And can I assume you answered it?”

“Well, I don’t work on the switchboard, but it did eventually come to me, yes.”

He seemed satisfied and turned back to Rob, with Millie’s notes still in his hand.

“This appears to be a combination of notes taken from a telephone call I had with Mr Milford. Oh, must have been… well, the day before he died, I believe.” He looked at the paper again. “But also, some of his own subsequent conclusions.”

“Millie brought you tapes?” Rob asked.

“Yes. Mr Milford brought me a series of magnetic tapes. I facilitated the reading of the reels and provided him with a list of statistical anomalies. We also carried out some interpretation of the data based on its operational use. These are the results.”

Susie leant forward. “Statistical anomalies?”

“Yes. Sections of data that didn’t fit into the surrounding context.”

“I’m sorry, could you explain a bit more?” Rob asked.

“Well, let me put it in more practical terms. Now, as I understand it, the data was gathered by a new form of height-measuring device on board an aircraft? A laser beam?”

“Millie really did trust you.” Rob smiled at the thought of the two men together.

“In the end he had to, otherwise I would have found it difficult to complete the tasks he set. Anyway, you would expect the height readings to look consistent with an aeroplane travelling across the land, but let us say that within a time period of less than a second, the height reading showed a difference of one thousand feet. Well, your aircraft would be physically incapable of manoeuvring at such velocity, and therefore the data must be wrong.”

“So you proved that the system was faulty?”

Belkin considered this for a moment. “We have to be careful drawing such conclusions. Mr Milford thought it possible that small inaccuracies might happen very often, but they would not likely interfere with the flight, as true readings would flow through before the aircraft’s autopilot would have time to make any changes. What he wanted to know, therefore, is how often inaccuracies lasted long enough to affect the flying. We provided this answer. We also used those numbers to make projections using actual flying statistics.”

“And the conclusion?” Susie asked.

“You have it on this piece of paper. Here…” Belkin pointed at a figure on the sheet. Rob leant forward:

0.9816%

“That’s how often we saw some sort of deviation. But this figure is the more interesting one.”

0.014%.

“That’s how often the figures could be wrong long enough to affect a flight. One and a half tenths of one per cent.”

“That doesn’t sound very often,” Susie said.

“True. If you only flew, say a hundred times a year, it would statistically never occur. However, the Royal Air Force flies rather more than that. And as I understand it, we should also consider the flying carried out in the United States of America?”

“Yes,” Rob said. “We should. So how often are we talking?” He looked at the figures again. “I’m sorry, my maths isn’t quite up to it.”

“Quite often. Without a pencil and some graph paper I can’t tell you exactly, but maybe a hundred times every ten thousand hours flown.”

Susie leaned forward, hands on the table. “You’re telling us, this system would cause one hundred crashes in ten thousand hours?”

“No. Again, there is another layer below this. For the vast majority of those occurrences, the incoherent data would cause a small deviation, but not enough to be a major problem. Mr Milford was keenly interested in very specific circumstances. Low-level, high speed and banked or approaching rising ground, and for the deviation to instigate a downward deviation rather than cause the aircraft to rise.”

He picked up the paper. “This, I believe, is his conclusion.”

Rob crouched down next to Belkin and peered at the sheet. “I still don’t understand the figures.”

“This is a classic application of statistics. Mr Milford has started with the number of flights, here…” He pointed at the number 262 . “And down here is an extrapolation from the data of the more serious anomalies. As I recall, it was a very low number and yet because of the sheer volume of flights every year, it appears that 3.5 flights annually would be critically endangered. I must say, from my recollection of our findings, this is about right.”

“Hence the 8.75 figure at the end. He’s averaged the crew size across the low-level fleet and come up with 2.5.”

“2.5 times 3.5?” Susie asked.

“8.75,” Rob confirmed. “The number of lives in danger annually if Guiding Light goes into service. Here it is, Susie. Here’s the evidence, in black-and-white.”

Susie turned to Belkin.

“Professor, where is the actual evidence? Do you still have the tapes and the data?”

“I’m afraid we destroyed them, on Squadron Leader Milford’s instructions. But there is something else rather important here. These conclusions are not reliable. There simply wasn’t enough data. Not nearly enough. The true figure, that number at the end, has much that is assumed and extrapolated from a very small sample size. I imagined this would be the beginning of an investigation, not the end.”

Rob didn’t reply; Susie rested a hand on his shoulder.

“I’m sorry if that’s unwelcome news.”

They sat in silence for a while. Rob toyed with the sheet of statistics. He stared at the final figure.

8.75

“Shall we have that tea now?” Belkin said.

The three of them drank from old mugs that looked like they’d seen service in the war. Belkin told them he’d stayed on Lundy with his wife Winifred the year after they were married in 1931. She was hit by a bus and died, crossing the road in Edinburgh in 1942.

“I thought she was safe up there.”

“Where were you during the war?” Rob asked.

“I suppose I can tell you now. I worked at Bletchley Park. Have you heard of it?”

Rob shook his head.

“I have,” Susie said. “Ultra.”

“That’s right. Your friends across the river.”

“We had a couple of lessons on it during training,” said Susie. “It was amazing. They captured the German code machines and cracked them. For most of the war, we were one step ahead. They never did find out.”

“So this was child’s play in comparison,” said Rob.

“Yes, it was a tough assignment. Much pressure on our shoulders and frequent setbacks. Rationing the information was the biggest challenge. If we used too much of it, it would be obvious we’d cracked the Enigma machines and the precious supply would suddenly end.” He poured himself another cup of tea as he spoke. “I never did get used to the idea that we would let a ship sink and all those men die, just to keep our secret safe.”

“But it was the right thing to do,” Susie said.

“Yes, it was. It shortened the war considerably and saved many more lives in the long run.” Belkin stirred in another sugar.

“You think this is how Kilton sees Guiding Light?” Rob asked Susie.

“Undoubtedly. He’s done these figures. With more data, his numbers will be more accurate, no doubt. Maybe higher than 8.75 men a year, maybe lower. But either way, he clearly considers it a price worth paying for the advantage gained.”

“But Mr Milford did not think it a price worth paying,” Belkin said. “And neither do you, Mr May, do you?”