“What is it?”

The cop shrugged. “He said it was shit from some truck treads. But that’s nuts. Must’ve been kidding.”

“No,” Rhyme said, “that’s exactly what it is.” He glanced at Cooper. Tire scrapings from the crash site.

The cop blinked. “You wanted that? Flown in from Chicago?”

“We’ve been waiting with bated breath.”

“Well. Life’s funny sometimes, ain’t it?”

And Lincoln Rhyme could only agree.

Professional flying is only partly about flying.

Flying is also about paperwork.

Littering the back of the van transporting Percey Clay to Mamaroneck Airport was a huge stack of books and charts and documents: NOS’s Airport/Facility Directory, the Airman’s Information Manual, the FAA’s NOTAMs—“Notices to Airmen”—and advisory circulars, and the Jeppesen “J-Aids,” the Airport and Information Directory. Thousands of pages. Mountains of information. Percey, like most pilots, knew much of it by heart. But she also wouldn’t think about driving an aircraft without going back to the original materials and studying them, literally, from the ground up.

With this information and her calculator she was filling out the two basic pre-flight documents: the navigation log and the flight plan. On the log she’d mark their altitude, calculate the course variations due to wind and the variance between true course and magnetic course, determine their ETE—estimated time en route—and come up with the Godhead number: the amount of fuel they’d need for the flight. Six cities, six different logs, dozens of checkpoints in between . . .

Then there was the FAA flight plan itself, on the reverse side of the navigation log. Once airborne, the copilot would activate the plan by calling the Flight Service Station at Mamaroneck, which would in turn call ahead to Chicago with Foxtrot Bravo’s estimated time of arrival. If the aircraft didn’t arrive at its destination within a half hour after ETA, it would be declared overdue and search-and-rescue procedures would start.

These were complicated documents and had to be calculated perfectly. If aircraft had unlimited fuel supplies they could rely on radio navigation and spend as much time as they wanted cruising from destination to destination at whatever altitudes they wanted. But not only was fuel expensive to begin with (and the twin Garrett turbofans burned an astonishing amount of it); it was also extremely heavy and cost a lot—in extra fuel charges—just to carry. On a long flight, especially with a number of fuel-hungry takeoffs, carrying too much gas could drastically erode the profit the Company was making on the flight. The FAA dictated that each flight have enough fuel to make it to the point of destination, plus a reserve, in the case of a night flight, of forty-five minutes’ flying time.

Fingers tapping over the calculators, Percey Clay filled in the forms in her precise handwriting. Careless about so much else in her life, she was meticulous about flying. The merest act of filling in ATIS frequencies or the magnetic heading variations gave her pleasure. She never scrimped, never estimated when accurate calculations were called for. Today, she submerged herself in the work.