British Airways deplanes 20 because of hot weather: How weight and balance is affected by heat
August 26, 2025
A British Airways flight from Florence to London City was delayed earlier this month after around 20 passengers were reportedly asked to disembark when hot weather meant the Embraer 190 could not take off safely from the Italian airport.
The incident, which occurred at Florence’s Airport during a spell of high summer temperatures, highlights one of the less visible aspects of aviation: weight and balance, and the performance limitations of certain aircraft at some airports.
While the removal of passengers can seem unusual, it is a recognised, if undesirable, aspect of airline safety procedures when environmental conditions affect aircraft performance.
Impact of hot weather on aircraft performance
Hot weather reduces the local air density, also known as increasing the ‘density altitude’, which in turn lowers the lift generated by wings and the thrust produced by engines.
Aircraft, therefore, require longer distances to get airborne.
At airports such as Florence, where the runway is shorter than average, high temperatures can create a situation where the aircraft cannot depart at full load.
For reference, Florence’s runway extends to 1,560 m, versus Milan Malpensa, which stretches to 3,920 m. As it happens, London City also has a short runway, at 1,508 m.
In such situations, airlines must reduce weight, sometimes by offloading cargo, sometimes by taking on less fuel, and occasionally by denying boarding to passengers. If the fuel needed to reach the destination would still push the aircraft above its maximum performance-limited take-off weight, then only cargo, passengers, or a mix of both can be offloaded.
The landing weight of an aircraft can also be a limiting factor, and this too is impacted by the runway length and available stopping distance.
The go-around gradient – effectively how quickly the aircraft can climb away from the ground in the event of an aborted landing – is also affected by aircraft performance and must be factored into weight and balance calculations.
Deciding how much fuel – and how many passengers – to take
In fact, weight and balance management underpins every commercial flight, and is a starting point for pilots before fuelling or boarding has begun.
Flight deck crew and dispatchers must ensure the aircraft stays within strict safety margins, not only in terms of total load but also how that weight is distributed.
If the aircraft’s centre of gravity shifts too far forward or aft, it can affect handling, stability, and fuel efficiency. This is particularly relevant during take-off when the aircraft is at its heaviest.
The Florence case is far from isolated. Airlines operating from airports with short runways, high altitudes or hot climates frequently face payload restrictions.
The southwest United States and the Middle East are the regions with airports where extreme summer temperatures can have an operational impact.
Added to that, most commercial aircraft are certified to operate within defined environmental limits, which set the maximum air temperature permitted at different pressure altitudes.
When those limits are exceeded, flights cannot legally or safely depart.
When extreme temperatures impact operations
In June 2017, temperatures in Phoenix, Arizona, climbed to 120°F (49°C), surpassing the certified threshold for the Bombardier CRJ.
As a result, several flights operated by that type were cancelled because conditions exceeded the aircraft’s approved operating envelope.
Technology has helped streamline the process. Modern load management systems calculate safe take-off weights and balances instantly, replacing the paper charts once used by crews.
But the fundamentals remain the same: hotter, thinner air means a reduced performance margin.
Aircraft manufacturers are working to reduce these limitations with more powerful engines and lighter composite materials. For the majority of shorter runway airports, which are constrained by their surroundings and not able to expand, this will, over time, reduce the operational impact.
Even so, decisions like those taken in Florence will always remain part of the equation when pilots and airline operations teams decide on routes, aircraft and payload.
And increasing temperatures around the world linked to climate change are likely only to exacerbate the problem.
