"Forget It" — The Under-Inflated Tires of Flight 2120

A DC-8-61 on Hajj charter flew for four days on main-gear tires its own maintenance team knew were low. During an A-check tire pressure check on 7 July, the avionics specialist measured tires #2 and #4 below the prescribed pressures and told the lead mechanic; a mechanic later altered the only record of those readings, and no tire was gauge-checked again. A tire change planned at Accra on 10 July was abandoned after the project manager faxed "Do not let maint change wheels in Acc" to get the aircraft back on schedule. On the morning of 11 July at Jeddah, with passengers boarding, the lead mechanic asked for nitrogen; the contract facility's bottles were empty, the only other source meant delay, and the project manager — responsible for the schedule, not qualified to judge airworthiness — directed the aircraft to depart unserviced. During taxi and takeoff the #1 tire, carrying the load its under-inflated axle mate #2 could not, over-deflected and overheated. It failed early in the takeoff roll; #2 failed almost immediately after; a piece of wheel rim embedded in the left flap, and the gear was retracted with burning tire remnants into the wheel well. The fire took pressurization, hydraulics and finally the cabin floor and control systems. The aircraft crashed 2,875 metres short of the runway on the attempted return.

The official findings read like a procurement list of ground-side failures: pressures below dispatch minimum and known to maintenance (findings 3.2.5–3.2.6), the record altered (3.2.7), no check after 7 July (3.2.8), a schedule manager making an airworthiness decision he was not qualified to make (3.2.11–3.2.12), a lead mechanic who knew better and did not countermand him (3.2.13), and sign-off as fit to fly by a flight engineer with no involvement in the servicing (3.2.4). Nobody who touched the decision held the authority — or exercised the assertiveness — the decision required. It is the corpus's cleanest case that tire pressure is an airworthiness limit, not a scheduling variable.

1. Check tire pressures with a calibrated gauge at the intervals the maintenance manual requires — Douglas specified 180 psi for the DC-8-61 — and record the actual reading.
2. A tire below the maintenance manual minimum is a maintenance action, not a judgment call: the manual required a tire found below 146 psi to be replaced, together with its mate on the same axle.
3. Service with nitrogen from a verified source; if nitrogen is not available, the aircraft waits — availability of a cart is not an airworthiness variable.
4. Never alter a recorded reading. The check sheet is an aircraft maintenance record; the true numbers are the only protection the next crew has.
5. Release to service is made only by a person qualified and authorized to make it — a schedule owner's "Forget it" carries no airworthiness weight, and countermanding it is the qualified person's duty.

Frequency of knowingly dispatching on under-inflated tires is not quantified in public sources — but the report found that everyone aware of the low pressures had insufficient knowledge of the hazard of operating that way (Saudi PCA final report, finding 3.2.10), and its first recommendation asks for tire pressure sensors with cockpit indication on all public transport aircraft (recommendation 4.1).

Failure of tires #1 and #2 on the takeoff roll; wheel-rim debris into the airframe; burning remnants retracted into the wheel well; in-flight fire involving tires, hydraulic fluid, magnesium alloy and fuel; loss of pressurization, hydraulics and flight controls; loss of control on final approach. The aircraft crashed 2,875 metres short of the threshold of runway 34C. All 247 passengers and 14 crew died (Saudi PCA final report via ICAO Circular 290-AN/168, Synopsis and findings 3.2.16–3.2.27).