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Yesterday I flew from San Diego to Boston in a commercial 737 operated by Alaska Airlines. Before landing we spent almost an hour circling. When we finally landed, many passengers were surprised to learn that we were not in Boston; we were still 90 miles / 150 km away.

The flight attendants told us the pilots had been too busy to announce the diversion. When the captain finally made an announcement on the ground, he said we had been redirected because the wait for Boston was 60 minutes and "we only had about 10 minutes of fuel left."

The cause was snow in Boston. Many flights were cancelled. However, visibility was excellent where we were and the flight was smooth. So I was surprised that we were diverted.

According to flightaware, we started circling at approximately 4pm; we were diverted at 4:48pm and landed at BDL at 5:03pm. Our scheduled arrival time was 5:06pm. (We departed on time.)

Below is the flight path (source).enter image description here

I was hoping that some people more knowledgeable than myself could help me better understand what was going on.

  1. Does "10 minutes of fuel left" mean 10 minutes until empty or 10 minutes until it becomes urgent? I find it hard to believe that there was so little reserve fuel, especially given that we were in the air for the scheduled amount of time.
  2. Would this situation count as a fuel emergency? Was it comparable to this incident?
  3. How low do commercial jets normally go fuel wise? In particular, how common is it to have 10 minutes of fuel left when landing?
  4. Can I find out more information about my flight online? I only know of flightaware. Is it possible to find ATC radio recordings?
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    $\begingroup$ Had I been the captain making that announcement, what I would have been saying was that at the point I diverted, we had 10 minutes of the fuel left that had been loaded for purposes of getting to Boston and doing any necessary holding. So at that point in the tanks there was 10 minutes of flying time fuel plus the fuel required to get to the filed alternate, plus the required reserve after that. What I would have been doing was diverting to the alternate 10 minutes before I was required to so for the simple reason that I was going to have to wait for 50 minutes beyond that time. No emergency. $\endgroup$ – Terry Feb 7 '16 at 4:47
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    $\begingroup$ @Terry Thanks. So you are saying the pilot meant "we had about 10 minutes of holding time left." That sounds reasonable to me. $\endgroup$ – Thomas Feb 7 '16 at 5:00
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    $\begingroup$ You can normally find ATC recordings at liveatc.net. Funnily enough, their KBOS feeds are down right now because a cable got cut due to the snowfall (I guess from a plow or ice accretion on aerial lines/tree branches.) If you post a separate question regarding finding the ATC recordings, you can probably get better help finding the right feed(s) than leaving it combined with all of these other questions. By the way, welcome to Aviation.SE! $\endgroup$ – reirab Feb 7 '16 at 5:00
  • $\begingroup$ To summarize: When starting the hold, the captain was at about equal time from KBOS and KBDL (10 mn). He holded for a certain amount of time. When he had 80 mn of fuel in tanks, he was informed that he would have to wait 60 mn more. He calculated he would land with fuel in tanks for 10 mn (which would be used to taxi). He decided to fly to KBDL alternate, where he likely landed with 70 mn fuel left. Without holding time for KBOS he would have had the same quantity when landing at KBOS. Nothing seems wrong or related to an emergency here. $\endgroup$ – mins Feb 7 '16 at 12:51
  • $\begingroup$ Thanks for the great answers. It sounds like the captain just chose his words poorly. $\endgroup$ – Thomas Feb 7 '16 at 17:01
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There appears to be no emergency. The flight was diverted at 16:58 EST and landed at Bradley International Airport at 17:03 EST. The same flight on 6th Feb landed at Boston at 16:46 EST. So basically, the flight was in the air only for an extra 15 minutes, compared to the scheduled time.

According to § 121.639 Fuel supply: All domestic operations.:

No person may dispatch or take off an airplane unless it has enough fuel—

(a) To fly to the airport to which it is dispatched;

(b) Thereafter, to fly to and land at the most distant alternate airport (where required) for the airport to which dispatched; and

(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption

So basically, the pilot diverted because the holding time was another 60 minutes and that would've eaten into fuel reserves.

  • I think the captain meant that the aircraft had only 10 minutes of fuel till he had to dip into reserves (or fly the alternate- it depends) and diverted because of the 60 minute waiting time. He could've been more clear though.

  • The pilot would've declared a fuel emergency if there was one. So, I think there was none.

  • Its quite uncommon for aircraft to land on 10 minutes of reserve fuel, though it has happened. In fact, some aircraft have run out of fuel.

  • You can find details about the ATC in liveatc's audio archives.

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  • $\begingroup$ What is the "where required" qualifier in the 121.639 section for? Are there situations where filing an alternate is NOT required? $\endgroup$ – curious_cat Feb 7 '16 at 8:48
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    $\begingroup$ @curious_cat Yes. There are situations where filing an alternate is not required. See this questio and this aopa document $\endgroup$ – aeroalias Feb 7 '16 at 9:25
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I feel like this was just a poor choice of wording by the captain.

It is extremely rare for an aircraft to land with just 10 minutes of fuel remaining, though it has happened before. In most cases, a jet needs to land with at least 30 minutes of fuel in the tanks, plus a variable percentage on top depending on the trip length - plus the airline-specific Ops Specs may require even more, and sometimes a specific airport warrants extra fuel for holding purposes. If the weather doesn't look too good, the plane needs to carry even more fuel to reach another airport, without using these minimums.

So I suspect the pilot meant he had 10 minutes of holding time, before he would have dipped into these minimums. Doing so is a big no-no and the authorities will need to be notified, hence the diversion before that happened. If my suspicion is correct, this did not count as an emergency.

As for your last question, liveatc.net is where you can find most ATC recordings. And if I am wrong and the pilot meant there was 10 minutes of fuel in the tanks, you should see the details on avherald.com soon!

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