Is the F-16's cockpit pressurized? If so, why does the pilot receive oxygen from the mask (please state the correct terminology for this)? Is it due to redundancy in case cabin pressurization fails?
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asked Jan 5, 2020 at 20:23
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$\begingroup$ Related: Do jet fighters have air conditioning systems? $\endgroup$– user14897Commented Jan 5, 2020 at 21:57
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1$\begingroup$ Related. Maybe a dupe, despite not being specific to the F-16? $\endgroup$– PondlifeCommented Jan 5, 2020 at 23:35
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3 Answers
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Yes, the cockpit of the F-16 is pressurized. However, there are two types of cabin pressurization:
Isobaric Pressurisation: The system maintains a constant cabin pressure (usually between 2000 and 8000 ft) as the atmospheric pressure decreases. This is used in commercial aircraft.
Hypobaric Pressurisation: In such a system the pressurisation commences at a given altitude and cabin altitude is maintained at this value until a preset pressure differential is reached. With continued ascent the pressure differential is maintained. This is used in military aircraft including the F-16, as the weight penalty of the Isobaric system would seriously affect the range.
Provision of supplemental oxygen in the aircraft ensures that the occupant receives increasing quantity of oxygen in the inspired air. The aircraft oxygen system (regulator assembly) ensures that the correct percentage of oxygen is added from the on-board Oxygen reserve to the inspired air in order to maintain lung pO₂ at 103 mm Hg.
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$\begingroup$ Do you have any technical documentation for further reading? $\endgroup$– Manu HCommented Jan 6, 2020 at 10:08
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2$\begingroup$ The ATPL Oxford manual of human performance and limitations should have a chapter on hypoxia or pressurisation $\endgroup$– ArnavCommented Jan 6, 2020 at 10:39
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1$\begingroup$ I'm looking for technical documentation that explains why those values, how is oxygen added on this particular aircraft's air system, and many other items related to the F16's pressurisation system. Side effect: most of it would also support your answer. $\endgroup$– Manu HCommented Jan 6, 2020 at 10:44
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$\begingroup$ Might be worth qualifying it as partial pressurization (which is what "hypobaric pressurisation" means). $\endgroup$– NatCommented Jan 6, 2020 at 19:30
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$\begingroup$ Does "lung pO₂ at 103 mm Hg" correlate with fingertip spO₂ monitors? $\endgroup$ Commented Jan 7, 2020 at 22:01
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Source: F-16 Flight Manual (T.O. GR1F-16CJ-1)
It is pressurized yes. Above you can see the schedule. Note that at high altitudes the cockpit altitude would be considered high (low pressure) and insufficient to avoid hypoxia.
If the oxygen system (OBOGS) fails, the procedure is to "Descend to cockpit altitude below 10,000 feet", which is about 24,000–26,000 feet based on the pressurization schedule.
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7$\begingroup$ This is one of those cases where a picture really is worth 1,000 words. Nice answer. $\endgroup$ Commented Jan 6, 2020 at 19:42
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$\begingroup$ What is the difference between Cockpit and Aircraft altitude, how can aircraft be at altitude 25 while cockpit is at 10? $\endgroup$– BuksyCommented Jan 8, 2020 at 11:56
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$\begingroup$ @Buksy: Because of pressurization, the cockpit altitude is lower than the outside. $\endgroup$– user14897Commented Jan 8, 2020 at 13:00
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2$\begingroup$ @ymb1 I think you missed the point of his question. The layperson understanding (and most common definition) of altitude corresponds to either absolute altitude or true altitude, based on height. Pressure altitude (based, unsurprisingly, on pressure and not height) is very aviation specific and not immediately obvious to someone outside of/new to the field. $\endgroup$ Commented Jan 8, 2020 at 15:14
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$\begingroup$ so in the chart the aircraft altitude = true/absolute altitude and cockpit altitude = pressure altitude inside cockpit? $\endgroup$– BuksyCommented Jan 10, 2020 at 12:18
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Yes. Like most fighters the cockpit of an F-16 is pressurized, primarily for pilot comfort. Use of an oxygen mask is required equipment for high altitude operations and for emergency situations. The pilot has a pressure breathing on demand oxygen mask, which is required equipment for high-altitude operations.
answered Jan 5, 2020 at 21:54
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2$\begingroup$ I believe that the F-16 can operate in excess of FL500, and generally, a pressure suit is required for operations above FL500, in the event of cabin depressurization. Use of a mask assures high levels of O2, without causing the risks which a pure O2 environment in the cabin would have (fire primarily). Survival above a pressure altitude of 50,000 feet is possible, with 100% O2 breathing, but only for a short time. So the pressurized cabin permits F-16 pilots from needing bulky and vision restricting pressure suits in normal operations. $\endgroup$– mongoCommented Jan 6, 2020 at 14:27
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1$\begingroup$ But typically an F-16 operates between 15,000 and FL350 and there may be ops policies restricting altitudes without proper life support gear. $\endgroup$ Commented Jan 6, 2020 at 14:38
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$\begingroup$ The F-16D flight manual shows a service ceiling of 18km, which is approximately 60,000 feet. Routine maneuvers may exceed the service ceiling. The cabin pressurization is indicated for flight safety. If not operational, there are altitude restrictions, as it is required equipment. $\endgroup$– mongoCommented Jan 6, 2020 at 14:57
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3$\begingroup$ No, routine maneuvers in a Viper do NOT exceed that ceiling. While one might be able to get a Viper up that high on a good day with no ordnance and minimal fuel, that does not represent typical day to day operations which are usually in the teens to mid flight levels (you need thicker air for good engine power and to maneuver). As for pressurization for flight safety, keep in mind that one minute in an F-16 is the difference between brakes off and rolling and leveling off at FL250 at 400 KIAS. That’s a hell of an inner ear workout if you don’t have pressurization systems to compensate. $\endgroup$ Commented Jan 6, 2020 at 19:33