“Professor Belkin?” called Susie.
He didn’t immediately answer, but concentrated on the last few steps. Rob went forward to help him down.
He steadied himself on the flat ground that ran around the cottage.
“I am he. To what do I owe this pleasure?” Belkin said, and gave them a warm smile.
“I’m Robert May and this is my colleague Susie. Perhaps we could go inside?”
“Yes, if you like. I have little to offer, I’m afraid, but I could rustle up a cup of tea. Or maybe something stronger?”
He opened the door, which wasn’t locked.
“Arrive in that thing, did you?” Belkin said, motioning toward the airstrip.
“We did. I’m afraid it’s rather urgent.”
The professor took a seat by the door, next to a small cabinet. “Perhaps one of you would be kind enough to make the tea? The fresh air does rather take it out of me. But I enjoy feeling tired. It’s one of life’s pleasures when you get to my age.”
Susie got up and moved to an old range at the side of the room. She found a stainless steel kettle and a china teapot.
“Professor Belkin, we’ve taken a considerable risk to visit you today. In fact, believe it or not, the RAF is currently looking for that aeroplane we arrived in.”
“I see,” the old man said.
“Can I ask you if you have ever met Squadron Leader Christopher Milford?”
The professor considered the question for a moment. “Perhaps you should tell me why you’re here.”
Rob glanced at Susie; she gave a small nod.
“I’m very sorry to tell you that Millie died in an aircraft accident on the 24th June.”
The professor bowed his head. “Oh, dear me. That is terribly, terribly sad. I am so very sorry to hear that.”
“Thank you, Professor. He was a good friend. But I’m afraid I rather failed in my duty to him. We’re here to make amends.”
“Did the bastards kill him?” the professor asked with nonchalance, as if this was a perfectly reasonable question in the circumstances.
Rob again looked at Susie.
“We don’t know,” she answered. “Maybe.”
The professor nodded, appearing to accept this as a potential outcome for Millie.
“After Millie died,” Rob continued, “they found out what he had been up to. They’re currently trying to portray him as a traitor, but we know better. We know he was trying to prove a new guidance system was fatally flawed, and that the trial to see it into service was a sham. I believe you may have helped him?”
The professor didn’t answer. Susie left the tea-making and moved from the kitchen area, pulling a piece of paper from her pocket. She unfolded it and handed it to Belkin. He put his reading glasses on and held it up to catch the light from the window.
Susie sat down at the table.
Eventually, the professor relaxed his hand, let it drop to his lap and looked at them expectantly.
“So, what do you need to know?”
“What does it mean? What did you find out?”
He looked across to Susie. “I can see that Mr May is with the Royal Air Force, but may I ask about your role, miss?”
“Attenborough. Susie Attenborough. Can I assume it was you who passed a certain telephone number to Mr Milford?”
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.”