The “Whys” of Airline “Ground Stops” For Passengers
For many passengers, flying is an unfamiliar, sometimes confusing experience made all the more so by the lack of understanding of inconveniences like ground delays.
Often it seems such take-off delays are arbitrary (the sky is clear and blue; let’s go!) and unfounded–but if you understood the reasons behind departure delays, you could at least keep your blood pressure low and your patience intact.
The most common–and often dreaded–delay term you might hear regarding your take-off is “Ground Stop,” which means you are not being allowed to take-off or more succinctly, your flight is stopped on the ground at your departure airport.
Multiple reasons. The most common is that the destination weather is such that the the number of inbound aircraft the Air Traffic Control can sequence is restricted or reduced.
Why? Well, the most common problem is a low ceiling and visibility that requires expanded spacing between aircraft.
Why more spacing? Because if we as pilots can separate ourselves from other aircraft visually on an approach and landing, we need only five miles of separation. If we’re flying in reduced visibility, that separation requirement at least doubles to ten miles. That cuts down the number of arrivals possible per hour.
But it could also be a beautifully clear day and capacity could be limited by winds. If the wind velocity or even gusts approaches the crosswind limitation of most aircraft–normally around 30 knots–then some runways may be unusable.
Why? This happens at DFW now and then because of the seven runways, five are oriented north-south, two are northwest to southeast. Doing the math, two runways rather than seven handling arrivals will of course mean delays.
The Ground Stop is a temporary way to shut off the flow of inbound aircraft until such time as either the limiting condition dissipates at the destination field–and that could be the low ceilings and visibility, winds or a thunderstorm. The last problem–a storm–can also cause a ground stop for your destination even after it passes.
Why? Sometimes it becomes a question of real estate: if a storm at your destination has stopped their outbound aircraft from taking off, there often is simply no room to taxi and park a slew of inbound aircraft. This is particularly true at small, congested airports like LaGuardia and Washington Reagan, but even large airports like DFW can become gridlocked as well.
And if the condition slowing things down is icing, there really is no point in allowing too many aircraft in.
Why? Because once an aircraft is de-iced, a take-off must be accomplished promptly or the deicing fluid loses its effectiveness and the plane needs to be de-iced over again.
What about when you’re told there’s an “outbound Ground Stop” for your airport? Rare, but it happens.
Why? From a pilot standpoint, the airport isn’t exactly “closed.” But the problem becomes the departure corridor: if the radar controllers can’t find a clear path for departing aircraft, they simply don’t allow any departures. But sometimes when your airport’s weather is fine, the departures from another nearby airport might cause a temporary shutdown of your airport’s departures.
Why? Well, as in the case of JFK, Newark, and LaGuardia, or Baltimore, Washington, and Dulles, or Chicago O’Hare and Midway, DFW and Love Field, or San Francisco International and Oakland and San Jose, and LAX and any of the dozens of airports there–if one field has bad weather, particularly thunderstorms, their inbound and outbound aircraft have to maneuver off of the normal routing in order to avoid thunderstorms. Air Traffic Control will wisely limit the number of new aircraft added to the mix.
Really, a Ground Stop makes sense when you think about it. Because the limiting condition at your destination would still exist whether you take-off or hold on the ground. So the problem with allowing the take-off even though the landing field is restricted is that you end up with a larger risk of delay.
Why? Because if the delay inbound is absorbed in the air, that means holding. If holding time is projected to be over a half hour or maybe even forty-five minutes, the end result will be a diversion.
Why? Well, because there’s only so much fuel we can carry en route since every aircraft has a maximum landing weight. If you add an extra hour’s worth of fuel–about 10,000 pounds on my jet–but then it turns out that you don’t need it to hold enroute, you could easily be too heavy to land. Guess what happens then: you will get to hold until you burn off the excess fuel, which is a tremendous waste and will guarantee that some connecting passengers’ next flight will depart without them.
Plus, in my pilot mind, after about forty minutes of holding, my air sense tells me it’s time to find a better place to land. It’s simply not prudent from a pilot standpoint to arrive at an alternate without extra fuel for contingencies there. And if we do have to divert, depending on how long my crew and our duty day has been, the FAA may mandate that we’re done flying for the day–which means you are too, wherever we are.
But all of that can be avoided by holding on the ground at our departure airport, burning no fuel. As frustrating as that may seem, the alternative is actually worse and really, taking-off without a good probability of being able to land at your intended destination doesn’t really sound like a good idea, does it?
I have to say, some crewmembers don’t even understand all of the Ground Stop factors I just explained and certainly, most passengers don’t either.
But the wise passengers like you who understand this “big picture” explanation of the dreaded Ground Stop can just take a deep breath, nod wisely and be confident that they’re on the optimum route to their destination.