Question: Why can't you land without dumping all that fuel? My GF lives within a mile as the crow flies to Dulles. Regularly we go outside and smell kerosene. If it's humid or foggy, it really strong. I've always wondered why all the dumping in a populated area.
First, nobody is regularly dumping at low altitude over Dulles.
FAR requires a minimum of 4,000 feet for jettison. High enough that the fuel should atomize.
Next, it depends on the airplane and circumstance. 747-400 for example, had a maximum takeoff weight of 875,000 lbs. Maximum landing weight of 630,000 lbs.
So, fully loaded for a Pacific crossing, it was 245,000 lbs above maximum landing weight. Unless it was on fire, the crew would jettison that fuel (some would be burned by the engines to stay aloft, most would be jettisoned) to get the airplane down to max landing weight.
On a normal flight, our fuel planning is actually very precise, and don’t show up at our destination over landing weight. In fact, it is often not even close.
Fuel is money. Big money. 30-40% of the cost of running an airline, so we don’t just load it up and dump it. That would be incredibly foolish, wasteful, and expensive. No airline could stay in business long with that kind of practice.
I have been close to maximum landing weight on arrival. It was always carefully planned. For example, EWR - KEF in a 757. Weather in Iceland that day was terrible. Winds gusting to 48 knots (about 55MPH), heavy crosswinds, low ceiling, heavy rain. We were planned to land at near maximum weight, so that we had enough fuel (nearly 30,000 lbs) to get all the way to Scotland if we could not land in Iceland. Glasgow, in fact. Not close, but we needed a good weather alternative, and there isn’t much in Iceland when the weather is bad in Keflavik, Akureryi, for example, has mountainous terrain, a short runway, and equally bad weather.
So, we carried the fuel to get to Glasgow, nearly 1,000 miles away.
But most times, we are well below maximum landing weight.
Even if we don’t have to jettison fuel, carrying extra fuel costs money. The heavier the airplane, the more it burns in flight to stay in the air. So, for example, back to the 747. If we added 10,000 extra lbs in Hong Kong, then flew to LA, we would burn over 2,500 of those pounds to carry that extra fuel. We would land with about 7,000lbs more in LAX. It costs gas to carry extra gas, so we rarely carry extra.
I don’t know what you’re smelling in Dulles - but it isn’t jettisoned extra fuel, I assure you.
I knew the airport was going through some work, and my initial thought was that returning there would absolutely wreak havoc on schedules, etc.
Yeah, not going back to SFO was a huge courtesy to other flights, other airlines, and the thousands of passengers that would have been impacted if the landing ended up with the airplane stuck on the runway.
Remember, we all know that the landing was uneventful. We know that now. The crew did not know it at the time. All they knew was that a wheel had been lost. Could be from a failure of that wheel itself, or it could have been from a failure in the landing gear structure. Hindsight is a wonderful thing, from which they did not have the benefit. If the landing gear had been structurally damaged, that airplane might’ve had a failure on landing that shut down the runway for hours. So, knowing that 28L was closed in SFO, it was a very prudent, thoughtful decision to divert to LAX.