Aviation systems manufacturer Collins Aerospace will soon begin testing its latest combat ejection seat for installation in the US Air Force’s (USAF’s) legacy Boeing F-15E fighters.
The Advanced Combat Ejection Seat 5 (ACES 5) is the successor to Collins’ widely-used ACES II system.
That rocket-powered ejection seat is installed in numerous military aircraft, including the F-15, Lockheed Martin F-16, Boeing B-1B bomber, Lockheed F-22, Northrop Grumman B-2 stealth bomber and the Fairchild Republic A-10 ground attack jet.
The ACES II was first fielded by the USAF in 1970s, and the service says the ageing ejection system is in dire need of modernisation.
The legacy system was designed before pilots commonly wore helmet-mounted displays and night vision equipment, leading to greater potential for head and neck injuries during ejection with modern equipment.
In addition to safety concerns, ACES II was also fielded when pilots were exclusively men – meaning the ejection system was not designed to work with lighter-weight aviators.
After winning a $700 million contract in 2020 to replace the ACES II, Collins now says it is preparing to begin certification testing the ACES 5 for integration with the F-15E.
“I would say we’re deep into the execution right now,” says Donald Borchelt, director of ACES business development at Collins.
Borchelt, a former F-15C pilot who goes by his USAF callsign “Dozer”, says Collins has completed the early development milestones for ACES 5 integration with his old aircraft.
“We’ll start sled testing that later this year,” he reveals.
Following the completion of certification testing, Collins plans to get production approval from the USAF sometime in 2025, which will cover ACES 5 seats for the service’s 218 F-15E Strike Eagles. Older F-15C/Ds, which the USAF is seeking to retire, will not be included in the retrofit.
Boeing’s latest F-15EX variant is currently equipped with ACES II. Dozer says Collins is in discussions with the air force to add the Eagle II to the ACES 5 programme.
Although ACES 5 production has not yet begun for the F-15, Collins is already producing the latest ejection seat for another USAF fighter: the Boeing T-7A jet trainer.
The air force separately selected the ACES 5 for integration into the new single-engined training fighter, of which Boeing delivered the first example last September.
Three T-7s have since arrived at Edwards AFB in California for USAF flight testing ahead of a low-rate production decision.
Borchelt says after testing is complete on the F-15, Collins will begin ACES 5 evaluations for integration with the F-16. The company is currently working with the USAF to develop an F-16 qualification programme.
Separate qualification and production plans will subsequently be developed for the other ACES 5 aircraft, including the A-10, B-1 bomber and F-22 stealth fighter.
Assembly of the new ejection seats is already underway in Colorado Springs, with the current contract covering the delivery of an indefinite quantity of ACES 5 systems through 2030.
Collins notes the ACES II is credited with 710 “saves” since its fielding more than four decades ago, including a rare four-person ejection from a B-1B bomber at Ellsworth AFB in South Dakota in January.
Borchelt says ACES 5 will provide an even safer and more reliable option for the last resort escape manoeuvre.
A new Passive Head and Neck Protection System will reduce the possibility of ejection-related spinal injuries for pilots wearing helmet-mounted displays and devices.
ACES 5 will also allow for safer ejection at higher speeds – certified for egress while travelling as fast as 600kt (1,110km/h).
The new seat will also be designed to work a much larger range of pilot weights than the ACES II – for which the USAF required functionality between 63.5-90.5kg (140-200lb).
The ACES 5 will substantially expand that range, accommodating pilots weighing between 46.5kg and 111kg.
Borchelt says the ACES 5 will also dramatically simplify regular maintenance compared to its predecessor, reducing lifetime sustainment costs for operators.
“The seat was designed from the beginning to be disassembled very simply and very easily inside the cockpit, without having to take off the canopy,” he notes.
By contrast, servicing the ACES II requires removing the cockpit canopy and ejection seat with cranes – a process Dozer describes as a “multi-hour, if not multi-day event”.
As Collins moves into performance testing, Borchelt says the ACES 5 will undergo an “extremely high level of scrutiny”.
However, he notes the new ejection seat is performing “extremely well” in evaluations thus far.
There are currently some 6,000 ACES II ejection seats in service worldwide, according to Collins.
Story updated 16 February to reflect that the current ACES 5 contract only covers F-15Es and not F-15C/Ds
