This week, Delta Air Lines was forced to temporarily shut down flight operations after its computer system failed.
It took four days for the second largest airline in the world to recover from the disruption to its operation.
As a result, Delta was forced to cancel more than 2,000 flights while delaying thousands more.
Unfortunately, Delta is just the latest airline to suffer a catastrophic disruption to its service.
American, United, Southwest, and JetBlue have all been forced to temporarily ground its fleet in the past two years.
This leads us to ask the question — why do airlines suffer mass shutdowns?
“There are two kinds of mass cancellations — strategic and non-strategic,” Phil Derner, NYC Aviation founder and FAA certified flight dispatcher, told Business Insider in an interview.
A strategic mass cancellation occurs when the airline has the opportunity to plan out the action. For instance, when an airline plans for an incoming hurricane or blizzard by completing certain flights to move its crew and aircraft out of harms way while cancelling others. A non-strategic mass cancellation happens suddenly and without warning.
“What happened to Delta this week was a non-strategic shutdown,” Derner said.
So, what’s is going on at an airline when a mass cancellation event does occur?
The daily operations of an airline is a neatly coordinated series of crew and aircraft movements. As an airline transports its customers, it’s also strategically shifting its crew and equipment to various parts of the network.
As a result, when Delta’s network was crippled by a computer outage this week, its crew and aircraft movement stopped along with the passenger traffic.
In statement this week, Delta wrote:
When Delta doesn’t fly aircraft, not only do customers not get to their destination, but flight crews don’t get to where they are scheduled to be. When this happens, unfortunately, further delays and cancellations result. And flight crews can only be on duty for a limited time before rest periods are required by law.
Flight crews — pilots and flight attendants — carry out their responsibilities in a rotation, a schedule of flights and hotel reservations, that is usually three or four days.
As cancellations occur, rotations become invalid. Multiplied across tens of thousands of pilots and flight attendants and thousands of scheduled flights, rebuilding rotations is a time-consuming process.
Airlines are in the business of making money. A flight cancellation could cost them tens of thousands of dollars. As a result, they prefer their planes to be up in the air generating revenue as much as possible. This means that the plane you are flying on is likely to have made as many as eight flights in one day depending on the duration of the trip. So if a plane gets grounded on its first flight of the day, there’s a ripple effect down the line.
So when an inbound flight operated by a 400-seat jumbo jet is cancelled, the next flight waiting to use that aircraft will need to find a replacement if it wants to keep to the schedule. And if there’s only a single 160-seat 737 available at the airport, then that flight is in jeopardy of delay or cancellation unless a replacement aircraft can be secured from another location.
While airlines do keep a few spare aircraft (usually of the most common aircraft type used for routes to that particular airport) around for eventualities, they aren’t enough to the cover the overflow of passengers from a mass cancellation event.
This also applies for the crew. Even though airline such as Delta place pilots and cabin crew on standby throughout its global network just in case of an emergency, there’s no way they could accommodate a shutdown of this scale.
Large international airlines operate fleets that could feature more than a dozen different models of aircraft – each deployed for a specific mission. Unfortunately, not all pilots are certified to fly all planes. In order for a pilot to be legally permitted to fly an aircraft, he or she must be “type rated” on the model. This basically means that the pilot must be licensed to operate that specific aircraft.
For instance, you are waiting for your delayed flight from New York to Paris on a wide-body Boeing 777. Even if your plane is at the gate, there may not be a crew available that’s type rated for the aircraft. And even if there is a crew certified to fly the plane, the flight may still be canceled or delayed.
Because the flight crew may not have enough duty hours left in their work day to complete the trip.
Pilot fatigue has been cited as a cause for some of the most devastating accidents in aviation history. As a result, the number of hours a pilot can be on duty is strictly governed by federal regulations under FAR Part 117 as well as labour contracts negotiated by the airline and the pilot’s union.
Strict duty hour limits also apply to the cabin crew.
At the end of the day. When you can’t fly, neither can the airline’s crew and equipment. Rest assured, the airline wants to make that flight happen way more than you do.
NOW WATCH: Inside Delta’s 2.7 million square-foot facility where they repair and maintain their massive fleet of aeroplanes
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