flying through a storm
On December 8, 1963, a Pan American Boeing 707 operated Flight 214 from San Juan to Philadelphia. There were 73 passengers and 8 crew on board, all systems were operational and the flight continued normally. While approaching Philadelphia at 8:42 p.m., the air traffic controller notified the pilots that a squall line with high winds, showers, and thunderstorms had been detected near the airport. The crew was asked to proceed to the holding area until the storm passed; aircraft commander George Knuth agreed. The wait should not have exceeded half an hour; flight 214 and five other planes were waiting for the storm to end.
At 20.58, the pilots suddenly went on the air: “MAYDAY MAYDAY MAYDAY” [аналог SOS]. Clipper 214 lost control. Well, it has started!” A few seconds later another plane, also waiting to land nearby, contacted: “Clipper 214″ burst into flames.”
The plane crashed into a cornfield east of Elkton, Maryland, at 8:59 p.m. Patrolman Don Hash quickly arrived at the scene of the accident. “There was no major fire. A few small fires were seen. When I got there the only large piece that was recognizable was part of the fuselage with about 8 or 10 windows. It was just a debris field. It didn’t look like a plane. “Due to the impact, the engines sank into the ground about 3-5 meters.” said HE.
Not a single person on board survived, and relatives were not allowed to be identified – it was impossible to do this visually. Mosaic-like facial pieces were placed on the mannequin’s head, but most people could only be identified by their teeth and fingerprints.
It was the first Pan Am jet to be lost in a crash and also the oldest jet in service. But this was not the cause of the disaster.
Investigation
Pan Am Boeing 707 crash site
historical community of Cecil County
At first, aviation expert investigators believed that the cause of the crash was damage to the aircraft due to turbulence. This version was not very convincing and therefore a bomb and lightning strike hypothesis was added to it. All three theories seemed strange, as crews of other planes reported that winds were relatively calm, and terrorist bombings of planes were not yet common at the time. The lightning version was absolutely great, because of this not a single aircraft was lost in the entire history of the United States. The investigation was complicated by the fact that the black box was designed to withstand an overload of 100 g, but 200 grams was tested. Therefore, experts manually restored the tape recording, which was 95% successful.
Detailed analysis of the wreckage showed that the aircraft caught fire at cruising altitude before crashing, apparently causing an explosion on board. This was confirmed when a wing tip with traces of high temperature exposure and a characteristic bulge was found a few kilometers from the crash site. Such traces are left by lightning, but scientists and aviation industry experts rebelled against this version.
During normal operation, an aircraft is struck by lightning about once or twice a year, sometimes damaging it slightly but not disabling it. However, reanalysis of the entire left wing revealed numerous scars and extensive damage consistent with lightning.
Additionally, seven of the 140 witnesses interviewed saw lightning strike from the side, and seventy-two claimed that the fire in the sky appeared simultaneously with or immediately after the lightning strike. Therefore, researchers had to record the first case in history when an aircraft was destroyed by electrical discharge from lightning.
The temperature jump in the area where the lightning struck caused the fuel vapors in the tanks to ignite and cause a fire. In this regard, the US Civil Aeronautics Board launched a series of experiments designed to find out under what conditions an electrical discharge could cause a fire due to the fact that the fuel practically cannot burn inside the tank. The situation was further complicated by the fact that there were two types of fuel on board, one of which ignited more easily at low temperatures. Pan Am conducted a test flight on its own initiative to see if the shaking caused by turbulence would cause the tanks to leak, since kerosene would ignite more easily outside. The result was negative.
Despite the most expensive research in aviation history (about $ 1.2 million at 2022 exchange rates) and the participation of many scientists, it was not possible to understand the specific cause of the fire. “Lightning ignited the vapors in an as yet unknown manner“, — Wrote As a result, experts. The Elkton plane crash was the largest mass fatality caused by lightning.
Does lightning threaten planes?
A few years later the Council updated the aircraft design requirements to reduce the risk of the incident recurring. Therefore, all objects located in the wings near the tanks, especially fuel tank covers, relief valves and maintenance hatch covers, now had to be grounded to the fuselage. Flame arresters were added to the fuel tank’s drainage (ventilation) system, which can inject fire extinguishing mixture in case of fire.
Additionally, the thickness of the aluminum in the wings was increased to reduce the likelihood of the discharge burning and reaching the tanks. They also tried to optimize the composition of the fuel, but none of their qualities could seriously reduce the likelihood of accidents, so new standards for jet fuel were not introduced at that time. Lightning protection in general coming down Creating a conductive electrical path in the aircraft that can withstand large currents.
Modern aircraft are very well protected from lightning: at least one discharge cannot set them on fire and bring them down like an anti-aircraft missile.
The last major plane crash caused by lightning occurred more than 50 years ago. According to the International Air Transport Association, on average, a plane is struck by lightning every 1,000 hours of flight. After that, the crew can continue the flight along the route or land at the nearest airport. After landing, technicians must inspect the aircraft and repair any damage. Mostly there are none, and airlines avoid paying for onboard downtime.
Source: Gazeta
Barbara Dickson is a seasoned writer for “Social Bites”. She keeps readers informed on the latest news and trends, providing in-depth coverage and analysis on a variety of topics.