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About That Sonic Boom Over Washington
A tragedy in the air, and another on the ground.
An F-16 like those that intercepted the Citation jet that flew to its doom over Washington D.C. this weekend. (Getty Images.)
This post is about two news-making sad outcomes, with a set-up for discussion of a longer-term ongoing challenge.
1) Yesterday’s sonic boom over Washington DC.
As a kid, I thought that sonic booms were just part of the daily soundscape. My K-12 schools were underneath the flight path for the gigantic Norton Air Force Base in San Bernardino, California. In those days of the Cuban Missile Crisis and the buildup to the Vietnam War, we’d hear sonic booms day and night—more and more frequently, the tenser Cold War relations became.
In modern urban life, ambient noise is rising but sonic booms are rare. Thus much of the DC area noticed yesterday afternoon when F-16 fighter planes broke the sound barrier over the Capital, on their way to intercept a Cessna Citation jet that crashed shortly afterwards in rural Virginia.1
Deb and I had just arrived in DC a few hours earlier, after two weeks in California, and somehow we didn’t hear the booms. But since then we’ve learned more about the incident. Here are the main points:
What happened: The big picture.
The Citation business-jet airplane, with four people aboard, flew from Tennessee to its intended destination on Long Island. The four people were: the pilot, the daughter and the 2-year-old granddaughter of the plane’s owner, and a nanny. The takeoff site was Elizabethton, a small airport in eastern Tennessee, and the destination was Islip, near a family house in the Hamptons on Long Island.
The plane made its northward course without apparent problem, and then seemed to turn to line up for a landing at Islip. But it never descended below 34,000 feet—a jet’s cruising altitude, and very far above the approach altitude for a landing. It overflew Islip and headed straight back over hundreds of miles toward the DC area. Planes flying at this altitude are required to be in constant touch with air traffic controllers. Reportedly this plane was “NORDO”—no radio, and no contact with anyone else.
The Citation finally crashed in a wooded area some 150 miles southwest of DC, on the hilly border between Virginia and West Virginia. This is where it apparently ran out of gas. On the map below, the blue arrow indicates the outbound course; the yellow arrow is the turning point, as if the plane were setting up for landing at Islip; the green is the straight-line path over Washington; and the red is where the plane apparently ran out of fuel and spiraled to the ground
Via FlightRadar24, the track of the plane toward its destination, and then to its demise.
Here is a closer look of the plane’s final descent. At the very end it was heading toward the ground at nearly 500 miles per hour, and losing altitude at over 20,000 feet per minute. This is a far more sudden descent than an airline passenger would normally ever experience. We can hope that all aboard were unconscious at this point.
Track of the final minute of the plane’s spiral, via ADSB Exchange.
Why did this happen?
As with everything in the aviation world, no one knows for sure, barely a day after a crash.
But several aspects fit the pattern of past aviation tragedies.
One is pilot incapacitation. Some news reports say that when the F-16s neared the plane they saw a pilot slumped over and unresponsive at the controls.
Why just one pilot in the cockpit? A plane like this would normally have two, but operators can apply for a “Single Pilot Waiver.” And what happened to this one pilot? A long-shot possibility is a heart attack or other sudden disabling event. That’s possible—though presumably the two other adults aboard the plane would have tried in the following hours to get on the radios or otherwise appeal for help.
The more likely explanation is that something went wrong with the pressurization system and oxygen supply aboard the plane, in a way that disabled everyone aboard.
The plane spent several hours above 30,000 feet in altitude. That high up, there’s simply not enough oxygen for people to function. Survive, maybe. Operate an airplane, no.
Decades ago, in preparation for a demo flight in the rear seat of an Air Force F-15, I was required to go through altitude-chamber training. You sat in a little enclosed cell, and minute by minute the oxygen was cut off—as if you were ascending into the “flight levels” and breathing only as much oxygen as the surrounding air would supply.
Every minute, you were supposed to write a few words on a note pad. By the time we got to the equivalent of 20,000 feet, my notations were a scrawl. By 30,000 feet, I could barely hold the pen. The shock was that I didn’t realize it at the time. The power of hypoxia is to reduce your performance and your self-awareness more or less in parallel. When I later saw a video of my few minutes in the chamber, it was hard to believe how semi-unconscious I had become. It was a physiological version of the Dunning-Kruger effect. I was being lobotomized, all unaware.
It left a permanent impression. Thanks largely to that experience, in my time as a small-plane pilot I have done my best to avoid extreme altitudes. Going coast to coast? Plan a path either north or south of Colorado’s dreaded Rocky Mountains. Need to go briefly to 10,000 or 11,000 feet to get through passes? Look obsessively at your fingernails, to be sure the nail-beds are not turning blue. Always have emergency oxygen aboard. And always look for the lowlands.
Of course staying low is not an option for business jets like the one in this tragedy. They are designed to fly in the 30,000-foot range.
Was there an “explosive decompression”—some mechanical fault that suddenly exposed all aboard to non-survivable thin air? Was it an insidious slow loss of oxygen, so gradual that no one noticed?
We don’t know yet. The most gruesome possibility is that only the pilot had a medical emergency, leaving the others in helpless awareness that the plane was going down. The more likely scenario is that whatever affected the pilot affected all the others too. Hypoxia makes you drowsy. So it’s more likely that they all were … asleep. This would be similar to a famous parallel case, which killed the golfer Payne Stewart and five others in 1999.
Why did they fly over DC?
This is another seeming similarity to the Payne Stewart tragedy. Stewart’s plane left Orlando for Dallas—and after the pilot passed out from decompression, it kept on going, until it ran out of fuel over the Dakotas. That seems to match the latest crash as well.
Based on what we know now, it appears that the plane was supposed to land at Islip, KISP, on Long Island. The reported winds at the time were from the southwest. That would favor a landing on Islip’s Runway 24—a long, broad, very comfortable runway.2 That is presumably what the pilots would have prepared for.
Why does this matter? Because—based on what we know now—it appears that the plane lined up on a heading of 240 toward Islip, as if getting ready for a landing on Runway 24. But then it kept on going, never descending from 34,000 feet, and flew in a bee-line on a 240 heading until it ran out of gas and crashed. The straight-line 240 course would explain the route over DC and beyond. [UPDATE: There is additional reason to think this is what happened, as explained in a footnote below.3]
Why didn’t the pilot notice? Why didn’t his and the others’ oxygen masks immediately deploy? Why didn’t he manage to descend, to a more benign altitude? Why didn’t anyone say anything over the radio? Might an oxygen problem have happened very early in the flight, soon after takeoff?4
We don’t know now, and might never know. Again let’s hope that everyone spent those last moments in slumber.
Was this any kind of threat?
Except to the people aboard, No.
Back in the 1990s, the skies over DC were like any other big-city airspace—and like New York, Los Angeles, or San Francisco even now. You could fly pretty much where you wanted, as long as you carefully obeyed instructions from the air traffic controllers and kept precisely to your assigned altitudes and headings. In those innocent days, I did a number of training and sight-seeing flights along the Potomac River past the Capitol, and up the Anacostia on the east side of town.
In DC that all changed after the 9/11 attacks. Airports in the region were locked down for months. Even now, you need special clearance to fly anywhere near DC.
Still, despite the warnings and penalties, some private flights manage to blunder their way into these restricted zones.5 To fly in the area, you have to take periodic refresher courses—including on what to do if intercepted by military jets.
From FAA instructions on what to do if you are surrounded by F-16s. You have to pass regular tests on procedures like this. In this graphic the errant aircraft looks like a big airliner. In reality the controllers are more worried about smaller planes going astray.
As a technical matter, the plane that crashed this weekend was so high when it passed over DC that it was not officially violating the airspace. The DC-area security restrictions go up only to 18,000 feet. The Citation was nearly twice that high when it passed over the Capitol and the White House, so presumably the F-16s were sent not to deter it but to see what was going on.
On some pilot message boards, there was early rumorology that the F-16s had finally shot down the Citation. That appears to be paranoia. The plane flew as long as it could, then it spiraled earthward—presumably because one engine quit just before the other, giving it unbalanced thrust at the end.
What do we learn from this tragedy? Mainly that it was a tragedy—as opposed to a threat. Maybe we’ll learn something further about oxygen systems. Maybe about unknown risks of single-pilot operation. Maybe about something no one has figured out so far. For now, this is sad and tragic. Sympathies to all involved.
2) This weekend’s business news out of Fresno.
Starting eight years ago, Deb and I have written frequently about the business, civic, and cultural renaissance underway in Fresno. Yes, that Fresno.
One of the central figures is this movement has been the startup tech company Bitwise—and its co-founders and leaders, Jake Soberal and Irma Olguin Jr.
We’ve known them; we’ve liked them; we’ve been drawn to their story and their example. We hired them to do web-site design for our little NGO. We wrote about them in our book. Mitch Kapor and Freada Klein did in their book as well. Here’s another illustration, from a piece I did two years ago, about Bitwise expanding its “inclusive opportunity” model from Fresno to other underdog, “left-behind” cities like Toledo, Ohio. And this, two years before that, about the company’s nationwide ambitions.
Jake Soberal and Irma Olguin Jr of Bitwise, in happier days. (Bitwise photo.)
Thus it is with profound sadness, puzzlement, disappointment, and sadness again that we saw this weekend’s news that Bitwise has suddenly ceased operations and laid off more than 900 employees, and that its board has fired the two founders, Soberal and Olguin, for apparent financial mismanagement.
I’ve sent queries to our many friends in Fresno, and will report back when I hear more. We’re reported on many stories of ongoing success, for instance with our friends at the Mississippi School of Mathematics and Science. We feel obliged to report the setbacks as well.
And speaking of setbacks, next up in this space we’ll return to the abyss known as Coverage of the Debt Ceiling. I’ll save that for next time.
I’m going to call the plane a “Citation,” not a “Cessna” as many news reports have. The Citation is produced by the Cessna company, but to many people “Cessna” suggests small, single-engine propeller planes like the Cessna 152, 172, and 182, which hold a maximum of four people (and all of which I have flown). The Citation is a business jet, which can hold up to 12 people. Anyone looking at it would think “corporate jet” rather than “tiny plane.”
As a reminder: runways are named for the compass direction of their layout. Runway 18 has a heading of 180 degrees, or due south. If you land in the opposite direction on that same strip of pavement, you’ll be on runway 36, or heading 360 degrees—due north.
To land on Runway 24, as this plane apparently intended at Islip, you would set up on a southwesterly heading toward the airport, at 240 degrees. That was the straight-arrow course this plane followed until it apparently ran out of gas, hundreds of miles later.
Update: The FlightAware log of this flight says that the filed route to Islip was
PSK GVE SIE BRIGS Q439 SARDI CCC. I won’t get into what that all means. The significant detail is the last waypoint in that list, before the destination of Islip.
The initials of that final waypoint, CCC, stand for the Calverton “VOR-DME.” This is a navigation beacon about 15 miles east of the Islip airport. CCC is also where the instrument approaches for Runway 24 at Islip begin. (For pilots: I am talking about the ILS / LOC 24 and the RNAV / GPS 24, both of which have their Initial Approach Fix at CCC.)
So a pilot planning to land on 24 would have loaded the PSK → CCC course, covering most of the flight from Tennessee to New York, into the autopilot. The pilot might also have loaded an instrument approach that would cover the final few miles from CCC to Runway 24. For reasons I needn’t get into, the route until CCC would be shown on FlightAware, but the final waypoints from CCC to the runway would not.
The path the plane took when it turned, as shown in the FlightAware image below, could indicate that the autopilot had been loaded with these final approach fixes. Or it’s possible that the approach wasn’t yet loaded, and the autopilot just calculated the curve that would take it from CCC, the last waypoint in its flight plan, to its destination airport.
Either way, the plane appears to have lined up perfectly for a landing on 24—even though it was still going full speed and was 34,000 feet up in the sky. (The autopilot appears to have been in “altitude hold” mode, rather than managing a descent.) Then, once the plane passed over the Islip airport (ISP in this image), the autopilot kept it steadily on the same 240 course, all the way to the end.
This image is from the FlightAware track, showing the plane making its big, 180-degree left-hand turn to line up with Runway 24.
Twenty years ago, when flying a Cirrus SR20 down to Kitty Hawk in North Carolina for the centennial of the Wright Brothers’ first flight, I was vectored by one air-traffic controller toward what another controller considered a brief violation of restricted airspace around DC. I had to fill out long forms explaining what had happened. Eventually: No harm, no foul. I still have a clean record with the FAA!