By Sanjeev Pathania
OCTOBER 2018, LION AIR: An aircraft took off from Soekarno-Hatta airport, Indonesia and was heading towards Pangkal Pinang city off Sumatra, but just 13 minutes after takeoff, lost contact with the air traffic controller and crashed into the sea at 6:33 A.M. All the 189 passengers onboard died in the accident. Both Captain Bhavye Suneja had more than 6,000 hours and his co-pilot Harvino had more than 5,000 hours of experience. They were flying a brand new aircraft – just off the shelf. So where did things go wrong?
MARCH 2019, ETHIOPIAN AIRLINES: A Nairobi, Kenya bound aircraft took off from Addis Ababa, in Ethiopia, but crashed within six minutes of being airborne. All 149 passengers and 8 crew members were killed.
MAY 4, 2019 MIAMI AIR INTERNATIONAL: — A charter flight operated by Miami Air International skidded off a runway at Naval Air Station Jacksonville and plunged almost immediately into the St. Johns River with 136 passengers and seven crew members on board.
VIRGIN ATLANTIC BOEING 747-400 A few years ago, a four-engine Virgin Atlantic Boeing 747-400 (a jumbo jet) aircraft lost a single engine due to engine failure over the United States en-route to the UK. The aircraft continued all the way over the Atlantic Ocean to the UK without any further problems.
MORAL OF THE STORY: An aircraft is most vulnerable almost like the proverbial sitting duck during the initial few seconds of takeoff. From a pilot error to stalling or engine failure there are a number of factors which can jeopardize the safety of people and aircrafts.
CHANCES OF AN ENGINE FAILURE:
The more you sweat in peace; the less you bleed in war. Scientific developments over the past decade have made engine failures, ever at high speed, extremely rare and maybe once a lifetime occasion for the pilots– in their real life or flying experience. According to surveys, less than one in one million flights will come across an engine failure or forced shutdown while take-off, landing or taxying. That’s where simulators come handy.
Pilots are put through a number of simulated situations to study their spontaneous reactions and prepare them for all possible scenarios using simulators every six-months. These exercises help reduce the chance of damaged aircraft, as well as men and fuel. It also helps them keep in touch and always alert to deal with all possible situations.
The simulators and other safety procedures have all contributed to make Air Crashes safer than bee sting, train accident, smoking or Cardiac failure. (See Box)
WHAT HAPPENS IF ONE OF THE TWO ENGINES FAIL?
Technically speaking a twin-engine aircraft can stay airborne; albeit at a lower altitude – carrying lesser weights even after losing one engine.
Once the aircraft is airborne, the pilots have to focus on take-off and control the aircraft till it reaches 400ft. The most challenging time for air-crash is engine failure between 400-to-1,500ft.
Once the aircraft reaches this altitude, the pilots habitually recall if they forgot something.
If a failure does occur, the engine is designed to contain any problems and stop it spreading to the rest of the aircraft. For example, if one of the fan blades at the front of the aircraft detaches, the engine casing should stop it leaving the engine.
WHAT HAPPENS IF ALL THE ENGINES FAIL?
Even if all the engines fail at a high altitude the aircraft may start losing height but can be made to glide down for 20 – 30 minutes till they reach a nearby airfield or anywhere else close by.
Aircrafts are able to fly through the movement of air over their wings. As long as this process continues the aircraft will continue to fly. If both engines fail, the aeroplane will not experience the push forward and start losing altitude.
Dual engine failure is something unheard of. An extremely rare and exceptional occasion was the Hudson River incident in New York in which everyone survived thanks to the response of the flight crew.
Another exception was the Air Transat Flight 236 where both engines failed due to a fuel leak but the crew managed to make a safe landing — 17 minutes after the last engine packed-up.
The fuel efficiency is directly related to engine power. Higher the power – higher the forward thrust – higher the fuel energy burnt in the engine and vice-versa. Hence to burn as little fuel as possible especially while descending the aircrafts reduce speed and go for minimum thrust while approaching the runway for touchdown. At this setting the aircraft is actually gliding.
A typical commercial aircraft has a lift to drag ratio of 10:1. This means that for every 10 miles it travels forward it looses 1 mile in altitude. If an aircraft is at a typical cruise altitude of 36,000 (which is 6 miles up) and looses both engines, it can travel a forward distance of 60 miles before reaching the ground.
All this is easier said than done. What really happens inside a single-engine military aircraft after its engine suddenly stop functioning — is a ghastly and unnerving experience that only someone who has been through can describe?
To experience this in real time Chief Pilot Steve Schmidt and Pilot William Berryman took off in a Boeing T-7A trainer and switched off the jet for close to 48 seconds before restarting the GE F404 engine at 20,000 feet and landing back at Boeing’s St. Louis site.
The success of the test which ratified all the critical development milestones is expected to have a positive impact on the first batch of T-7A Red Hawk which Boeing expects to handover to the U.S. Air Force in 2023.
The U.S. Air Force awarded Boeing a $9.2 billion contract to supply T-7A Red Hawk aircraft and training simulators in September 2018. The T-7A designed by Boeing and Saab has already been put through more than 175 hours of flight in over 160 developmental test flights.
According to senior Boeing officials the current test will not only bolster the confidence and reliability of the T-7A aircraft, but also that of the team designing and developing the new trainer aircraft for the US Air Force.
According to experts the purpose behind the current test was to allow the pilot to shut the engine down in an emergency and glide before switching on the power to restart the engine in mid-air. All this is requires lot of preparation, planning and teamwork.
