When I was a Check Airman for my airline, supervising new captains on their first flights in the left seat, I always did one thing consistently over a three day trip: about twenty miles from landing, I’d cover the fuel gages with my hand and ask, “How much fuel do you have?”
What does that have to do with your flight running late? Everything.
And here’s where the passenger in a time crunch and the pilot-in-command part ways: time, speed and fuel.
They’re interrelated and while we both share the goal of getting there, the pilots need to “get there” with as much fuel as possible. That’s because more fuel means more flying time available, which means more options. So by day three of my trip with a new captain, he always knew how much fuel–and thus flight time–he had available, because he (or she) knew I’d ask. After over 24 years as captain at the world’s largest airline, that’s a habit pattern I personally maintain to this day: fuel is time, and my job is to wring as much time as possible out of every drop of fuel on board.
No, that doesn’t mean I want to fly as long as possible–I want to be able to fly as long as possible. Big difference, but the reality is, if I don’t have fuel in reserve, I don’t have time in reserve either, and both are crucial in case of delays due to weather, peak air traffic volume and even mechanical anomalies. And that’s just in the terminal area on arrival.
Enroute, there could be more weather we need to fly around safely (more miles–and fuel–burned) plus, the optimum altitude might not be available or, if it is, there may be a dissimilar aircraft ahead for whom we’ll be speed-restricted, causing us to burn more fuel. Throw in the frequent Air Traffic Control reroute or off-course spacing vector, and you have a significant potential for fuel over burn above the planned consumption.
On a flight of more than three hours, even a 10% fuel over burn can significantly limit a pilot’s options on arrival: can I hold for weather and traffic congestion, and for how long, before I have to divert?
Add more air miles–and thus more fuel burn–to stay safely upwind of storms.
So we have the potential for weather and traffic delays, altitude restrictions and even mandatory re-routing by Air Traffic Control, all of which can and typically do eat away at our fuel reserves. These limiting factors can pop up at any time after takeoff and the fact is, there’s no more fuel to be had at that point, leaving you one option--save as much as possible enroute. Which means the highest, optimum altitude at the most economical speed.
Ironically, Air Traffic Control may even need you to fly a faster than optimum speed for a long stretch of time in order to equalize traffic flow, and you’d better have enough fuel to comply but still maintain your fuel reserves for arrival regardless.
Juxtapose that reality with the option of flying “faster to make up time.” First, a jet is not like your car–if you push the speed up ten percent, depending on your altitude, your fuel consumption may go up during the higher speed cruise by 20-30%. But how much time would you make up? Over a three hour flight, maybe ten minutes at most. Is that worth blowing all of your options, especially knowing that destination areas delays could wipe that out anyway? Is it prudent to fly hellbent-for-leather to shave off a fraction of the delay at the cost of having zero options once you get there?
Fuel and time: the buck stops here.
The answer, of course, is no, it doesn’t make sense to “speed up to make up time.” Believe me, no one wants to finish the flight any sooner than the working crew, but never at the expense of what we know lies ahead, and therefore, what makes sense.
Certainly, you can ask the pilots to “fly fast,” but the result will be predictable no matter what you may hear.