Autopilots on modern fighters
 

Curious about the capabilities of autopilots on modern fighters, I would imagine in the past they have been fairly basic but what about Typhoon / Rafale / F22 etc ?


Can they, for example fly an entire route with different waypoints, level off at a preselected altitude, fly a 'Vnav' descent to a predetermined fix, or an ILS approach, even an autoland ?


I believe the F18 can fly an automatic approach to a carrier ?


Any fighters with autothrottle(s) ?

Autopilots on modern fighters
 

A single F/A-18 had been used by Boeing in the development of autoland software. It never made a full landing under autopilot but demonstrated the technology for use with a drone which has made successful arrested landings.

Typhoon includes a system in case of pilot incapacitation that levels the wings and puts the aircraft into a slight climb. I do not know what logic it uses to establish G-induced Loss Of Consciousness has happened but that's how the system is advertised.

The USN were messing around with an auto-land system via datalink back in the early to mid 60s, using a numer of F-4G Phantoms, i think it was also linked in with the aircraft's existing autopilot...

-RP

Can't speak for "modern fighters" but the Tornado GR1/4 has a pretty good AP because it was designed to fly an entire route at low level, on Terrain Following Radar with the AP engaged. The autothrottle can maintain a selected groundspeed. The AP can fly a route at medium level but has no vertical nav function and cannot fly a procedure of any sort. I believe auto ILS was envisaged but never cleared for use.

The Super Hornet can indeed fly a route of waypoints and is capable of 'coupling up' to fly an automatic approach to the boat. The various pilot relief modes also include auto throttles both for en route and in the landing pattern.

I forget what the currency restrictions were, but suffice it to say that you weren't allowed to use the automatics to land until you'd mastered (and remained current in) the mandraulic approach...not something I was ever in danger of.

Tornado GR1 auto-ILS worked fine but yr correct it was never cleared. :oh:

Never tried it on the GR4 though.

Later Lightnings had a very good auto ILS. Would track localiser and glidepath accurately and had an auto throttle which held 178+/- 3 knots (as I recall). Rumour had it that a senior officer went into the barrier having failed to disconnect the auto throttle after landing from an auto ILS/auto throttle approach !? Anyone got more info on this?

Stilton,

Best way to help is maybe to give you a typical profile in a FJ. T/O and climb are normally flown manually. No need for A/T as the throttles are left at Mil power. At the TOC the autopilot can be engaged in an alt hold and heading hold mode. A/T can be engaged to hold the current speed (although I know some FJs have selectable A/T speeds). For small turns Hdg Sel can be used, and for long track legs you can fly direct to the waypoint. At the waypoint Hdg Sel can be selected to turn towards the next waypoint, or in Hdg Hold mode the pilot flies the a/c with the stick but when released the a/c rolls wings level into Hdg Hold again.

At TOD the A/P and A/T are disconnected and the a/c flown manually for app and landing. There are some relief A/P modes that allow a certain pitch attitude to be held, and these can be used if the approach starts to get busy. A/T can be used for the landing and approach (say to maintain 250kts in busy airspace), but that is up to the pilot. Many of us prefer to use manual throttles for landing as ironically enough its a bit smoother. We don't tend to have VNAV like an airliner so there isn't a VNAV PATH option, although as more and more jets get RNAV that may change.

Auto-approach is available in some a/c, but needs specific equipment to be serviceable, and given that it saves fuel, most FJ landings are visual approaches hand flown. Hope this helps.

F4, F15 - just a basic AP. F3 - cut down airliner AP. With auto ILS, and auto throttle to touchdown, but we weren't allowed to us it; unproven snag with the Radalt detecting the nose wheel or some such bollocks. Typhoon - as you might expect.

Very interesting, thanks for the informative replies, I'm surprised that autothrottles have been around for some time in fighters but I can see how it makes sense.


Couple more questions, any of these autopilots have a vertical speed / ias hold mode for use in climb or descent and lastly does your on board nav data base contain named civilian waypoints or even airways that you could proceed direct to or navigate on ?


I would doubt you would have a civilian data base like that as It would use up so much memory that you want for the military mission,I suppose you don't fly routes or to waypoints like us civilian types but just curious.

I recall reading a green line entry for the AP in on of the crows' jets at Wattisham (after the sqns had merged): 'Use with caution as +4g pitch excursions may be experienced'.....:eek:

Never used the wretched thing, except in the simulator to play with 'stick top steering'.

As for the switches spattered around the cockpit which were supposed to control the Buccaneer autopilot........:rolleyes:

Sort of
 

Stilton, while on 31 Sqn I did take the GR1 along the odd airway and do a little procedural work but it was not great and required planning and loading into a tape.

At that time Bruggen did sometimes use civil airports like Dusseldorf as diversion options but when poss preferred a local military base like Norvenich, Gielengkursian (spelt wrong sorry) etc.

Talking of F700 entries, I snagged an F3 autopilot once for " aircraft climbs/descends +\- 200ft with altitude mode selected" only to get the rectification response as " NFF, fault could not be reproduced on the ground". No sh*** Sherlock!! and We all know what NFF means!!

Stilton,

I think some FJs have a V/S mode (Tornado?) although none of the ones I've flown have. As for IAS hold, if you mean something like FLCH on an airliner, to the best of my knowledge no they don't….again at least not on anything I've flown.

CJ you're absolutely correct, the Lightning had a very good autopilot (Smiths MK 10 I seem to recall), You could use it either in Ht & Hdg mode or in Attitude Hold. In either mode you could select the autopilot and then fly the a/c on the 'little stick'

The incident you refer to did indeed happen. An Air Commodore (I think) wanted to fly the a/c solo and duly underwent a short course. Your first solo was at that time flown in the T4 so off our hero went. On finals to land, he decided to use the autothrottle to keep the speed @175kts but forgot to disengage on landing. He kept pulling the throttles back, not an easy task against the clutch, as soon as he released any pressure on the throttles they moved forward again trying to keep 175kts, the autothrottle won and the barrier saved the day.

The auto ILS was super, so accurate that the decision ht for an auto approach was lower than a manual ILS. There used to be a bit of discussion at Wattisham about the possibility of doing an auto ILS at Honington if you were really caught out by the Wx and lack of fuel and just letting the a/c hit the ground, Honington having an in-line ILS al the time, would have been quite exciting but some folk were quite certain they would give it a go.

stilton - the GR1 had a Mach Hold setting. With this, you were free to move the throttle and the AP would vary the attitude to maintain the Mach number - usually used in the decent, though rarely.

The Basic Mode of the Tornado AP also allowed you to simply engage AP with no other modes selected and it would hold the attitude selected. If it was very close to straight & level, it would automatically select straight & level for you (can't remember the range I'm afraid).

There's no "database" on the GR (or F3 afaik). You get a moving map with selectable scales on the GR so you can at least point towards it, you also have access to TACAN display, though not VOR. So whilst not strictly speaking legal to flying in Class A, in the past it was done fairly regularly. Main problems occurred when you were asked by ATC to steer towards some arbitrary beacon and you couldn't find it on the map to head towards. On my GR1 IRET, I flew an airways leg and a full IF approach into Stansted.....all from the back seat too! :eek:

When Binbrook was running down a few plumber mates and I (I was avionics or flight systems as it was then) blagged a ride in the sim. The boys flew it with varying degrees of success and then it was my turn. They were all amazed at the accuracy with which I flew it and of course I basked in their accolades, although I did forget to mention purely accidentally that I flew almost the whole sortie with the autopilot in...:ok:

Edit: I do remember the sim techs didn't like you slamming the throttles open, did something nasty to their magic boxes apparently.

Although not the best in the world the Tornado F3 autopilot was OK. Like all things, you had to know how to operate it to get it to work for you.
It was capable of:
Height hold
Heading/track steering
Route flying (both MC Route and JTIDS Route)
Mach hold (good for climbs and descents)
Auto throttle
Auto ILS (not cleared in RTS but very good. Could fly a 67 wing approach better than most pilots)
There was a plan to introduce a much more powerful AP to enable dynamic hands off flying for night/IMC intercepts/VIDs etc but like many things the money was pulled by MOD for other projects.

I flew 3500 hours on F3 and used the AP whenever appropriate. Why not reduce the workload and increase brain capacity for other tasks?

The F3 did have Twin INS fed by GPS and monitored through an MC. Although not as easy to fly down the old VOR based airways it would be easier to fly Rnav routes and procedures if cleared. Also difficult to legally fly a VOR or NDB approach when neither fitted. Very few knew how to use Tacan for VOR Approach!
Not sure about Typhoon but most probably still using "British Officer Coming Through" principle.

Thanks again for the great replies, very interesting.

What is a '67 wing approach' ?