Delta Air Lines parked 571 mainline aircraft across the country in 2020 when the COVID-19 wiped out most passenger travel. Airlines still have about 70% of their pre-pandemic international capacity in hibernation, but Delta is returning aircraft to the skies because the U.S. domestic market is recovering faster than in other parts of the world.
Parking a plane and bringing it back to life after months of inactivity isn’t as simple as turning the engines off and on. It takes a lot of effort, including maintenance and electrical checks, to keep an aircraft in a ready state for future use.
As the pandemic reached the U.S. in March 2020, Delta (NYSE: DAL) began parking aircraft in Blytheville, Arkansas; Kansas City, Missouri; Marana, Arizona; and Birmingham, Alabama. Each location had separate challenges, such as humidity, desert heat or bugs and small animals nesting in crevices.
In some regions of the world, for example, mud dauber wasps clog exterior speed-sensing tubes with mud. Maintenance personnel are instructed to regularly check the probe covers for damage.
So many aircraft were flown into the Birmingham airport that Delta technical teams ran out of the chocks placed by the wheels to hold the aircraft in place. Workers bought 6-by-6 skids of wood from local hardware stores to hand-make replacements, the airline said in a recent blog post.
Finding airports and fields that had room for aircraft was a big undertaking itself. In San Bernardino, California, a designated parking area wasn’t usable after a Boeing 757 began sinking into the pavement. And runways in Kansas City and Victorville, California, were only temporary, so the planes eventually had to be moved again.
Planes in long-term storage also need special covers placed over the engines and fuel to be removed if they are kept in a hangar.
Delta TechOps scheduled maintenance work for each aircraft at seven, 14, 30, 60, 100 and 180-day intervals. Coordinating the checks and spreading out the work required extensive planning, according to the airline. The engineers developed flexible “job cards” for each aircraft specially tailored to the climate conditions where they were parked, while conserving supplies and manpower.
“Putting an aircraft to sleep really hasn’t been done in the Delta world before. Some of the tasks have never been written for a lot of these airplanes because they were fairly new,” a maintenance program manager in Atlanta said in a Delta video.
The pandemic complicated the storage efforts. Most mechanics commuted to different storage facilities for periods lasting a few days to a month and couldn’t eat at restaurants because they were closed. At one location, a chief used the hotel kitchen to make meals for his team.
Many stored planes were stripped of certain parts to help repair planes in service. When it was time to reactivate them, mechanics had to find and reinstall new parts.
All planes reentering service have their systems activated and reviewed, and gears and components greased. Then they undergo a test flight before going to a repair facility for a maintenance overhaul, according to Delta’s blog.
Smaller planes can take about 10 days to two weeks to rehabilitate. Larger aircraft can take two to three weeks to fix up. The process is longer for planes stored 180 days or more, especially if there are expiring components that need replacement.
When the maintenance is finished, pilots arrive to fly the plane to an airport where it will pick up passengers and cargo.
So far, Delta has returned 493 aircraft to the active fleet. The company expects to be reactivating aircraft into 2022.