2
$\begingroup$

Consider a hypothetical situation where where an unexpected tailwind will cause a flight to arrive at its destination above maximum landing weight. After reviewing all reasonable changes to altitude and airspeed, it is clear that on the flight plan route nothing short of a hold or delay vector would allow for a landing within the weight limits.

The SIC suggests including the dispatcher in the decision, and asking for a delay vector or or hold that adds 8 minutes to the flight.

The PIC elects to land overweight, citing a regulation in FAR 121 that precludes any undue delay to burn fuel. Not a specific regulation, just that there is something like this in there.

Is there a regulation in FAR 121 (or any of the other 14 CFR/FAA regulations that govern the flight) that would be violated by adding distance to the route or a hold in order to facilitate additional fuel burn and a landing within the limitations?

$\endgroup$
  • 3
    $\begingroup$ There is a bit of a logical gap in this scenario. The only situation where you'd have enough fuel load to be at MTOW at departure and need to fly a significant time to get below MLW, would be a trip that is long enough that you simply couldn't arrive above MLW in any normal tailwind. For a trip where a tailwind could get you to destination with very little fuel burn where you could arrive above MLW, you wouldn't have started with that much fuel in the first place. Maybe if the airline was tankering fuel for some reason but that would be about it. $\endgroup$ – John K Dec 1 '19 at 19:13
  • $\begingroup$ I can't see this scenario being possible. MTOW and MLW aren't generally far apart, you don't have to fly for long. $\endgroup$ – GdD Dec 1 '19 at 21:26
  • 1
    $\begingroup$ @GdD A Boeing 747-8 has a MTOW of 987,000 lbs and MLW of about 675,000 lbs. That's over 300,000 lbs of fuel and about 2/3 of the max fuel capacity. $\endgroup$ – Gerry Dec 1 '19 at 23:17
7
$\begingroup$

This scenario isn't common but it isn't exactly rare, either. You take off with a full plane & lots of fuel for holding & an alternate, planning to arrive just at max landing weight. Then, due to shortcuts and/or better than forecast tailwinds, you under-burn & see that you'll arrive above max landing weight.

First, the hypothesized rule in Part 121 doesn't exist. Absent the Captain's use of his emergency authority (which does NOT require declaring an emergency to invoke, but which DOES have to be reported after the fact), what you can't do is "just go ahead and land overweight." That would be deliberately violating an operating limitation on the aircraft, and that's bad.

Second, there's typically no need to involve the dispatcher... just burn the gas. Holding, or extended vectors, or an early descent, or extending the gear way early... take your pick of what works best in your situation & then make it happen. Not a big deal.

Burning extra gas (really, just burning all the gas you'd planned to burn with the flight plan) is NOT a violation of anything in Part 121. On the contrary, intentionally landing overweight - in the absence of a circumstance making that the safest option - would be a violation.

Listen to ATC long enough, and you'll occasionally hear somebody ask for a delay to burn the extra gas. ATC can easily accommodate that; I've never heard it treated as if the crew is asking for something strange or suspect. Sometimes winds or shortcuts put you in that situation; it's nobody's fault, and it isn't a problem to burn the planned fuel.

$\endgroup$
  • $\begingroup$ Could one simply burn up the fuel without delaying, by intentionally avoiding the most efficient flight envelopes? Fly at 16000 when able to fly at 35000, fly at max speed instead of best cruise, etc. $\endgroup$ – Harper - Reinstate Monica Dec 2 '19 at 6:03
  • $\begingroup$ @Harper, yes, those are ways to burn fuel faster. Each has its pro's, con's, and limitations. For example, cruise altitude may need to be high enough to overfly bad weather, so that may be a bad choice "today". Depending on the flight duration, a higher cruise speed may not burn enough more gas to solve the situation. But both options could certainly be considered. $\endgroup$ – Ralph J Dec 2 '19 at 12:01
2
$\begingroup$

I did a little rooting around and from what I can find and from my own general sense the answer is no. No regulation could possibly be issued based on what is effectively a somewhat abstract environmental goal (or maybe an objective of really really cheap airline) that supersedes regulations related to safety or efficiency in the system.

That being said, maybe, theoretically, an airline may have done a business case where in that situation they decided the costs associated with the need to do an overweight landing inspection (basically just maintenance manhours as long as they crew does a nice gentle landing) was less than the cost of "wasted" fuel, and the airline would therefore authorize capts to land overweight if the wasted fuel was more than some threshold, but I think that is kind of "out there" and is pretty unlikely. I've never heard of such a policy on the Regional side of things, and perhaps one of the mainline-knowledge guys here can pipe in.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.