All U.S. F/A-18 Hornet models affected by oxygen deprivation and cabin decompression issues

Mar 29 2017 - 6 Comments

Legacy and Super Hornet showing a concerning steady increase in “physiological episodes” that U.S. Navy calls “No.1 safety issue.”

The F/A-18 Hornets of all variants seems to be affected by a serious issue: oxygen shortage, or hypoxia, is plaguing the fleet of Legacy (A/B/C/D), Super Hornet (E/F) and Growler (EA-18G).

As reported by Bloomberg News, the F/A-18 of all models have shown a steady yearly increases of what the Navy calls “physiological episodes” due to oxygen deprivation and cabin decompression since May 1, 2010.

Navy officials testifying before the House Armed Services subcommittee called the problem the “No.1 safety issue.”

And what is even more concerning is the fact that there seem to be little clue as to what is causing the issue.

The “lack of overall progress” is “of great concern,” said Representative Niki Tsongas, the top Democrat in the panel.

While investigating the issue (with a task force of 62 people), the U.S. Navy has also enhanced “reduced-oxygen training” so that pilots can quickly identify the symptoms of hypoxia. Two aircraft carriers have installed chambers for aircrews exposed to decompression.

According to Bloomberg News, 130 out of 383 episodes “have involved some form of contamination,” according to a Navy and U.S. Marine Corps official statement. 114 involved an environmental control system component failure, 91 involved “human factors” and 50 concerned a component failure with the on-board oxygen generating system.

Older versions of the plane, the A through D models, have problems with cabin pressure whereas the Super Hornet and Growler issues “would appear to point to the onboard oxygen generating” system to which the Navy’ has already made changes.

It’s not clear whether the issue affects also other international Hornet operators.

Not the first time

This is not the first time the U.S. forces face the oxygen deprivation issue.

A similar problem plagued the F-22 Raptor fleet to such an extent the radar-evading aircraft were grounded back in 2011 following a deadly incident involving an Alaska-based stealth jets.

In that period, the F-22 were experiencing 26.43 instances of hypoxia or “hypoxia-like” problems for every 100,000 flight hours, compared to 2.34 instances per 100,000 hours for the F-15E and 2.96 for the latest version of the F-16 (the Hornet was not part of the data set released back then.)

After lifting the flight ban, the Pentagon restricted Air Force Raptors to fly near a “proximate landing location” in order to give pilots the possibility to land quickly if their planes’ On Board Oxygen Generating System (OBOGS) failed.

In May 2012, two 1st Fighter Wing “whistleblowers” appeared on CBS 60 minutes to explain why they were “uncomfortable” flying the Raptor (before changing idea few days later).

The flying branch eventually determined a valve that regulated oxygen flow into the Raptor pilot’s pressure vest was too weak and F-22s were given a new backup oxygen system as part of multiple contracts awarded to Lockheed Martin (worth 30 Million USD) that automatically dispenses oxygen when OBOGS is not providing enough. 

Various problems

The news that all the kind of Hornets might be choking their pilots comes in the wake of a Super Hornet and Growler fleet-wide grounding and (concerning but for the moment totally unrelated) increase in crash rate, especially among the oldest models.

Nine incidents involved “Legacy Hornets” (including the Canadian CF-18 lost on Nov. 28, 2016) in the second half of last year, with the latest loss on Dec. 6, 2016, when a USMC F/A-18C crashed off Kochi causing the loss of its pilot.

In the wake of the Hornet crashes from June through October, the U.S. Marine Corps temporarily grounded its non-deployed Hornets. Unfortunately, few days after the ban was lifted, two more F/A-18Cs were lost.

The crash rate has affected the ability of the USMC to perform training activities while committing to support real operations: out of a requirement for 171 aircraft, the service had only 85 Hornets available for training according to a report emerged last year.

In order to address the shortage of operational fighters the Marine Corps has launched a plan to upgrade 30 retired legacy Hornets (currently stored at the 309th Aerospace Maintenance and Regeneration Group at Davis-Monthan AFB, Arizona) to a standard dubbed F/A-18C+: once upgraded these “gap fillers” should be more than enough to conduct combat operations in low-lethality scenarios like those that see the USMC at work lately. Still, they might not have a fix for the hypoxia issue.

“Trump’s favorite jet”

As a side note, in their story on Bloomberg News, Roxana Tiron and Anthony Capaccio call the Hornet “Trump’s favorite fighter jet.”

This is due to the fact that Trump has been advocating the Super Hornet since December 2016, when the then president-elect posted a pretty famous tweet that favored the Boeing combat plane over the Lockheed Martin F-35C.






  • Thomas Verhey

    The EF model (‘super hornet’/’rhino’) oxygen generator issue is a mystery, the navy has no clue what is actually happening, only that carbon monoxide is being pumped into the cabin instead of oxygen…. They tried a ‘stab in the dark’ fix, but that did nothing to solve or reduce the fatal issue/hazard.

    Either the Carbon monoxide is originating from other equipment in the jet and being funnelled by the pump or it’s coming from the generator itself… Testing has proven unreliable after a decade and millions of dollars.

    Being Carbon monoxide, the pilot and back seat have no warning, only when they are told by a wing, other seat, ground that they are irregular do they have any timely warning (analogous to not knowing you’re too drunk to walk until you stand up, but you’re never going to stand up) at the controls of a fighter jet…. Possibly upside-down, flying towards the earth, in a canyon, 2metres off the wing-tip of another who may also be breathing carbon monoxide.

    …. Now, please someone in Parliament, if you’re reading this… Print it out and then JAM IT IN TRUDEAU’S FACE, GLUE IT TO SINGH’S BRIEFCASE LID, STAND ON A DESK AND READ IT ALOUD WITH A MEGAPHONE…
    … Because so far, the loyalty to whatever disgusting pre-election promise to Boeing is winning out against counter promises to the Navy, RCAF, Budget & taxpayers….

  • Max

    They still havent solved that problem!? Wow, embarassing.

  • Rick Smith

    Well I would be looking in to what company contracts these parts out. I would be trying to follow the common thread until I figure out what is exactly causing this. It seems very obvious to me this can’t be a coincident it has to be connected.

  • John Larger

    I am surprised at the issue of oxygen deprivation in modern aircraft (F-22, T-45, F-18…). I thought we had this figured out back in World War II and on through the U-2 and SR-71.

  • WhoIsJohnGalt

    OBOGS problems on every aircraft where it is deployed. F-22, F-16, F-15E, T-45, F-18, F-35. WTH!?! Are we putting these devices that impact pilot performance and thus safety of flight into the field ‘hoping’ that they work!?! Where is the extensive instrumentation and test a system of this importance deserves?

  • SeniorChiefD

    I worked on the F18 for 10 years as an AME. We never had this issue on any A,B,C, or D models in my time. The first thing I would be looking at is who is supplying the molecular siev beds in the OBOGS system. These filters are designed to remove the argon and other impurities from the bleed air being delivered. This has to be the problem. If the military changed the supplier then the supply system would be easily checked by looking at the manufacturer. I find it hard to believe that AIMD is not catching this when bench testing the OBOGS generator. Always preferred LOX.