I've Always Wondered ...

What’s up with how airlines board planes?

Mitchell Hartman Dec 23, 2015
I've Always Wondered ...

What’s up with how airlines board planes?

Mitchell Hartman Dec 23, 2015

Listener Hutch Humphreys of San Diego sent Marketplace this question: “I was wondering what research has gone into the various algorithms airlines use for boarding passengers, and why most of those algorithms do not seem to work very well.”

Airlines have two principal goals in boarding. They want to turn the plane around as fast as possible to avoid delays and extra labor costs. And they want to differentiate between their most-valued customers and everyone else, in terms of the ease and comfort of boarding. So most airlines provide early boarding, first-shot at the overhead bins, perhaps a favorite magazine or complimentary drink once seated onboard as a perk for their premium customers — those with more expensive first-class or business-class tickets, airline-branded credit cards and the like. Then they board the rest of the passengers who bought cheaper seats in coach.

Most airlines board by the same basic method: Passengers with expensive tickets and other VIP-status first (along with passengers who need extra time and assistance getting seated), and then passengers in the main cabin. Delta invites all non-premium passengers in the main cabin to board at once. United has recently introduced a different method—boarding out-to-in, that is, window seats, middle seats, then aisle seats. Alaska Airlines boards from back  to front, in zones.

After finishing boarding a flight at Portland International Airport (PDX), Alaska gate agent Frances Sheehan offered a clear answer for what gums up the process the most: “too many bags,” she said.

Carry-on bags are the bane of boarding these days. Passengers try to bring them onboard to avoid checked-bag fees. Overhead bins fill up, bags have to be returned to the front of the aircraft to be gate-checked, lines stop moving.

Alaska now uses a computer program to calculate how many carry-ons will have to be checked at the gate on a given flight to avoid running out of overhead space, according to Gavin Graham, Alaska Airlines general manager at PDX.

Discount carrier Southwest is alone among the major airlines in using an open-seating method. Passengers line up for boarding based on how early they checked in. Once on the plane, there are no assigned seats: it’s first come, first served.

“Once you get on the airplane, it’s just like church or the movies. It’s a very egalitarian experience,” said Southwest spokesman Brad Hawkins. Checked bags fly free on Southwest, so there are fewer carry-ons, which helps Southwest achieve some of the fastest boarding times in the industry, said Hawkins.

Astrophysicist Jason Steffen at the University of Nevada-Las Vegas thinks boarding could be made much more efficient, though. He began researching the issue as a graduate student after being frustrated by slow boarding processes and flight delays.

“The algorithm that I used to find the optimal boarding method is called Markov Chain Monte Carlo,” said Steffen. “You set up a scenario, make random changes to it. If the random change is an improvement, then you keep the change, and if the random change is not an improvement, then you keep the change sometimes.”

Steffen’s research eventually took him to Hollywood, “to the studio where they filmed ‘Airplane,’” he said. “They had 72 seats, we got 72 extras, they all had some luggage. It turned out that boarding in blocks from back to front took about twice as long to fill the airplane as my method.”

The optimal method Steffen came up with, and published with colleague Jon Hotchkiss in the Journal of Air Transport Management (Experimental test of airplane boarding methods): Board the plane back-to-front, every other row, alternating sides, first window seats, then middle seats, then aisles.

Steffen said it’s more efficient, because it spreads passengers out, allowing them to find their seats, stow their luggage and get out of the aisle with minimal crowding in the passenger cabin.

Steffen also found in his research that random boarding — “to say, ‘OK everyone, airplane’s open, go ahead and get on board’” — would also be faster than the methods airlines use today. That’s because passengers who line up in random order for boarding are not likely to be assigned adjacent seats. So they’re less likely to be jostling with other passengers for room to maneuver and space in the overhead bins, before settling down to fly.


Delta Airlines Order of Boarding:

Pre-Boarding Zone:
Customers needing assistance or additional time to board, including families with car seats or strollers.

Premium Boarding Zone:  
Delta One™ customers
First Class customers
Diamond Medallion® members

Sky Priority Boarding Zone: 
Platinum Medallion® members
Gold Medallion® members
Delta Comfort+™ customers
Flying Blue Platinum and Gold members
Virgin Atlantic Flying Club Gold members
Virgin Australia Platinum and Gold members
GOL Smiles Diamond members
SkyTeam® Elite Plus members

Zone 1:
Silver Medallion® members

Priority Boarding Trip Extra customers
Gold, Platinum and Reserve Delta SkyMiles® Credit Card members
Flying Blue Silver members
Virgin Australia Velocity Silver members
GOL Smiles Gold members
Sky Team® Elite
Crossover RewardsTM SPG® Platinum members
Capital One World Mastercard® cardholders

Zone 2:
Main Cabin

Zone 3:
Basic Economy

SOURCE: Delta Airlines

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