Walk around any aircraft parked on a ramp and you will see them fluttering in the breeze: long red ribbons printed with three words in white capitals. REMOVE BEFORE FLIGHT. They hang from pitot tubes, landing gear, engine intakes and ejection seats, and they have become so iconic that you can buy them as keyrings and luggage tags.

Behind the souvenir, they are a serious piece of safety equipment. Each ribbon marks something that keeps an aircraft safe on the ground and could kill its crew if left in place for flight. And despite the bright colours, history shows that people do still forget them.

What the Red Tags Protect

Each tag is attached to a device that does a job on the ground. Pitot tube covers keep insects, dust and water out of the probes that measure airspeed. Landing gear pins mechanically lock the gear down so it cannot retract while the aircraft sits on the ramp or is being worked on. Gust locks clamp the control surfaces so the wind cannot slam them about. Intake blanks keep debris out of engines.

In a fighter, the most important pins go into the ejection seat. They stop the seat and its explosive charges firing by accident while ground crew or pilots climb in and out. They are removed before flight and fitted again once the aircraft is back on the ground.

Captain Joe explains what the remove before flight tags on an airliner are for. Video: Captain Joe

When Covers Are Not Removed

The worst accidents linked to ground equipment show why the system exists. On 31 March 1975, a Royal Nepal Airlines Pilatus PC-6 Porter crashed just after taking off from Kathmandu, killing five people, among them Louise Hillary and her daughter Belinda, the wife and daughter of Sir Edmund Hillary. According to Elizabeth Hawley's biography, as cited on Wikipedia, the pilot, who was running late, did not do a walk-around and failed to notice that an aileron was still secured by a ground lock.

On 2 October 1996, Aeroperú Flight 603, a Boeing 757, crashed into the Pacific off Peru, killing all 70 people aboard. Adhesive tape had been left over the static ports after the aircraft was cleaned and polished. The instruments gave the crew false airspeed and altitude, and the transponder sent the same false altitude to air traffic control. That tape carried no red streamer at all, which is precisely the point: anything that blocks a sensor has to be impossible to miss.

Mentour Pilot tells the story of Aeroperú Flight 603, brought down by tape left over the static ports. Video: Mentour Pilot

Streamers Are Not Enough

Even with bright red ribbons, pins get missed. On 21 June 2021, a Qantas Boeing 787 departed Sydney with its landing gear downlock pins still installed. The crew could not retract the gear and returned. The Australian Transport Safety Bureau investigation drew a clear lesson for the whole industry.

In other words, a streamer is a reminder, not a procedure. The ATSB stressed that crews and engineers must confirm the pin itself has been removed rather than trusting that a missing ribbon means a missing pin.

From the Ramp to the Keyring

A 2008 Canadian Transportation Safety Board investigation into a Hughes 369D helicopter crash found that an engine intake cover without prominent warning streamers had become entangled with the controls, contributing to the accident. It is the same story from another angle: the red tags work only if they are on every item and checked every time.

Pilots and ground crews count them. That is why pilots and ground crews check them on every walk-around. And for everyone else, the ribbon has become a symbol of aviation itself, sold on keyrings and bags worldwide.

An aircraft engineer explains remove before flight tags. Video: AIRCRAFT ENGINEER

Sources: Wikipedia (Remove before flight, Aeroperú Flight 603, 1975 Royal Nepal Airlines Pilatus PC-6 Porter crash), Australian Transport Safety Bureau, FlightGlobal