(For Korean version, go here)
At Sunday, some news agencies talked about the emergency landing of Delta Connection 4951. You can read exactly what went on here, but in a short version, a Delta Connection Flight 4951, departed from Atlanta to JFK, suffered a landing gear malfunction, which resulted in the one side of landing gear not sticking out. So the pilot made the emergency landing with sparks flying everywhere with 64 passengers and 3,000 ‘gallons’ of fuel. Fortunately, the spark didn’t reach the fuel, and all made out in one piece. It’s all good, but there was one thing that bothered me, and you can probably guess it from the quote-on-quote.
The sentence in question.
First off, let me start with a basic fact about avionics: avionic pundits usually use weight instead of volume for calculating the weight of fuel. Why? Because weight is more important. If you think about it, it’s kinda obvious because planes actually have to fly.
Anyway, the reason why I had doubts about this was because someone asked why didn’t 4951 dump the fuel before landing, since that was the basic procedure of emergency landing. (You know, because of sparks and everything) When I answered that there won’t be enough time to dump the fuel and land because there weren’t much fuel to begin with, and that person replied saying that 3,000 gallons is a lot of fuel. So, I decided to calculate myself how far 3,000 gallons will move the plane.
So, first step was to switch gallons into pounds, and that involves finding the density of the common jet fuel. Let’s Google this, shall we?
(Source)
Okay, got that. Now, let’s plug this in. After a quick unit calculation, I’ve found out that I have to multiply 6.76 into 3,000. Okay, launching the calculator…
What?
Okay that’s a bit weird. Of course I’ve heard that 3,000 gallons were a lot of fuel, but that’s too much. So I decided to plug in this data to the most possible plane model, the CRJ700, after searching for it in Wikipedia. (Seriously, it’s amazing that you can find almost everything on the web these days.) So the maximum carrying fuel is…
What??
Now there’s definitely something wrong. How can there be more fuel than there can be physically possible. But, it doesn’t hurt to keep going. The maximum range of CRJ700 is approximately 1,650 miles. Then, the gas mileage(?) would be around 11.39 pounds per mile. The flight distance from Atlanta to New York is around 746 miles, so multiply both, and we get 8,500 pounds. So, the plane has to use at least 8,500 pounds to get to New York. Yup, doesn’t make sense.
The conclusion? I guess all newspaper writers are similar. Always getting the facts wrong. I just feel like I did one of those proof thingys on math. (“Prove that the newspaper is wrong.”)
P.S After more calculation, if it was 3,000 pounds instead of gallons, the plane (assuming that it was CRJ700) could fly for up to 263 miles.
P.S 2 The answer to the question that started all of this proving stuffs was because usually planes that small does not have fuel ejection assembly.
P.S 3 The next morning after I wrote the Korean version that I used to write the English version, AP and CBS News indicated the fuel amount as pounds, gallons. Well, it felt good while it lasted.
