Tongdao Think Tank 2024-01-08 16:54 Published in Beijing.
According to a recent report by Mission and Objectives, an Air Force B-1B supersonic bomber crashed while trying to land at Ellsworth Air Force Base in South Dakota on January 4, and four crew members ejected safely.
This bomber was assigned to the 28th Bomber Wing in Ellsworth, which was one of the two B-1B bases of the Air Force. The bomber crashed around 5:50 p.m. when the crew was trying to land during a training exercise, according to the Air Force**. Three crew members have been discharged from the hospital after receiving ** for minor injuries. One pilot is being treated at a local hospital** with non-life-threatening injuries.
Whatever the cause, the accident drew attention to the bomber's ejection seats, which seemed to play a role in the accident as designed. But this is not always the case. Ejection seats are common in small fighters, but in large B-1Bs, there have been a few successful seat ejections and some failures that have led to fatal and near-fatal accidents in the past.
With a crew of four including a pilot, co-pilot, and two officers, the B-1 is the largest aircraft with ejection seats flown by the Air Force. All four crew members sit in advanced concept ejection seats or ACESII seats with escape hatches above.
In 2018, a B-1B engine**, the crew tried to eject, and the seat failed to ignite. When the ejection seat of one crew member did not "ignite" (meaning that the rocket that launched it from the aircraft did not ignite), the aircraft commander canceled the ejection of the rest of the crew. The plane was able to make an emergency landing. An investigation by the Air Force found that a non-functional, potentially aging part prevented the seat from following the ejection sequence.
The ejection failure led to the grounding of the entire Air Force B-1 aircraft until all seats were checked and allowed to fly.
In a fatal accident in 1987, six crew members flew on a B-1B, two of them in non-ejection seats. When the aircraft encountered an emergency, three ejection seats started correctly, but one did not, resulting in a pilot and two other crew members being trapped on board. Despite the fact that the B-1B had a final escape hatch in the cockpit floor, none of the three escaped before the plane crashed.
There are currently 6,000 ACESII seats in service, including the Air Force's fleet of A-10, F-15, F-16, F-22, B-1B and B-2. ACES technology was designed by Collins Aerospace, a subsidiary of RTX Corporation (formerly Raytheon Technologies).
Kevin Coyne, who runs the Catapult Stadium History Project and is a member of the Safe Association, a group of traffic safety experts, said it was a "fairly advanced seat, even though it's 50 years old," with some upgrades over the years.
According to RTX, the ejection chair was launched in 1978 and has saved 703 lives. "Unlike other seats, ACES has a less than 1% ejection spinal injury rate," a company spokesperson said.
The ejection system of the B-1B can be launched in a number of different ways and can be activated by any crew member to eject the entire crew. All four crew members can eject automatically in less than two seconds, although the system can choose a manual mode and each pilot can eject on their own. Collins Aerospace said both options are arranged sequentially to provide a delay between crew ejections to prevent collisions. When the crew pulls the ejection handle, the hatch above the crew is blown open, and then the rocket from the seat is launched.
According to one Collins a**, when the crew enters the airflow, the seat decides which of the three parachute modes to use.
Mode 1 is suitable for low-altitude flights from 0 to 250 knots (approximately 288 miles per hour), including take-off and landing. Due to the proximity of the bomber to the ground, the parachute on the seat was deployed immediately upon leaving the cockpit in order to inflate the crew before landing.
If the B-1B flies at a speed of more than 250 knots, the seat will activate mode 2, in which the conical sleeve parachute will stabilize the seat before opening the main parachute.
Mode 3 is used for high-altitude ejections, where the air is thinner to a dangerous degree. In Mode 3, the seat immediately deploys the cone sleeve parachute to stabilize the seat upon fall, but does not deploy the main parachute until it reaches an altitude of 15,000 feet (low enough for the crew to breathe).
An early version of the bomber, known as the B-1A, was initially equipped with a crew escape module, which covered the entire cockpit area and was "about the same size as a minivan," Coyne said.
The B-1 project, developed in the 70s of the 20th century, was canceled by Jimmy Carter in 1977, but resumed by Ronald Reagan. Reagan approved the construction of 100 B-1Bs as part of the defense construction. When the program was restarted, the US Air Force eliminated the crew escape module in favor of ejection seats due to weight and cost issues.