A video shared on Twitter showed the pilot in a high-visibility jacket loading suitcases onto a conveyor belt into the aircraft.
"This guy's a legend," says someone in the video.
Soon after, the plane was able to fly to Greece.
Passengers on the flight described Simon's act, which helped them make their air traffic control window, as "heroic".
Jenny Cook, who was a passenger on the flight, took to Twitter to urge Tui to give the co-pilot an 'excellence award'.
"Please RT @TUIUK @TUIGroup can we get Simon the co-pilot of the TOM2744 flying from Manchester on 30th may an excellence award ? He is out on the tarmac in the rain helping to load the bags to try and get us on our way after 30 hours delay so far," she wrote.
A Tui spokesperson said they were aware of videos "showing one of our amazing Tui pilots supporting our operation by loading bags on to one of our aircraft bound for Crete from Manchester".
While loading suitcases isn't part of the job description for a co-pilot, the spokesperson said it was an example of the "incredible dedication" Tui colleagues have to helping customers reach their destination.
Like many airports in the UK, Manchester Airport has struggled to meet the surge of demand, resulting in long queues and cancelled or delayed flights.
Manchester Airport confirmed that Tui and Swissport, which provide baggage handling services, were experiencing temporary staff shortages.
Tui announced it will cancel six flights a day this month "to provide stability and a better customer service".