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Assume an older IFR-certified aircraft with the classical equipment, that is two VOR/ILS receivers with plain CDIs, ADF and DME, but no GPS. It can be flown IFR, but many routes can't be used, because they use fixes that can't be found with this simple equipment.

If a suitable portable (that is, not built in nor connected to the aircraft systems) GPS unit is available in cockpit, and has appropriate aviation maps loaded, it it allowed to plan or accept an RNAV route that can only be flown using the GPS? What features and certifications does the GPS unit need to be usable this way?

Note that I am not thinking about any RNP procedure nor a RNAV approach (the ILS is there for approach in IMC), just normal en-route navigation over fixes defined by coordinates only. That way, the GPS is not critical—if it fails, I can always request vectors or rerouting over a navaid.

(If it differs over the world, I am most interested in European situation)

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  • $\begingroup$ Is the GPS rigidly mounted or hand-held? Either way, I doubt it will be allowed to be used for any safety-related function. $\endgroup$
    – quiet flyer
    Oct 5, 2019 at 16:30
  • $\begingroup$ The key point may be whether or not it is hard-wired into the aircraft's electrical system. $\endgroup$
    – quiet flyer
    Oct 5, 2019 at 16:38
  • $\begingroup$ It is definitely not wired into anything in the aircraft. It is mounted so that it does not get flung around in case of turbulence, but only so that it can be brought into the aircraft before flight and removed again after landing. $\endgroup$
    – Jan Hudec
    Oct 5, 2019 at 17:16
  • $\begingroup$ @JanHudec Im trying to find the exact reference but under the FAA I belive to be legal for RNAV routes (and approaches) the GPS needs to be panel mounted. $\endgroup$
    – Dave
    Oct 5, 2019 at 17:28
  • $\begingroup$ Although you're asking about EASA, you can also see this question for the US rules $\endgroup$
    – Pondlife
    Oct 5, 2019 at 18:37

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The answer, broadly is no, handheld GPS units can not be used for IFR RNAV routes (or approaches for that matter). To know if a specific GPS unit is legal for IFR navigation you need to check up on a variety of paperwork, thats covered in this answer. Strictly speaking if you could find a certified unit it would be legal but there are no current units (to my knowledge or searching) that are.

If we look at the regulations and bounce around a bit we can see why. AC 90-108 tells us about the use of RNAV systems and states that one must be compliant with installation instructions in AC 10-138D of which there are many different regulations. The AC does not actually specifically state that the unit must be panel mounted but in a round about way it does:

The definition of display which is used widely in the document does state it must be mounted to the panel,

Display. Within the context of this AC, a display is a device mounted in the aircraft instrument panel to convey course guidance navigation information to the aircrew for controlling the aircraft along the intended route. Displays may also be used to convey other information as well.

There are also lots of regulations about wire mounting to avoid issues and failures as well as other mounting regs. If you are interested its worth going through the document.

See Pondlife's comment bellow for more info on panel mounted GPS'

just normal en-route navigation over fixes defined by coordinates only. That way, the GPS is not critical—if it fails, I can always request vectors or rerouting over a navaid.

In order for the GPS to be non critical you must fly at altitudes serviced by other nav-aids. The reason GPS routes are coming into use is that they, in some cases, allow flying at lower altitudes that may be beneath ATC radar or out of range of nav-aid coverage. In the case of a failure of a GPS unit you would then be with no means of navigation and terrain avoidance.

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    $\begingroup$ See this answer for a more explicit FAA reference on panel mounting. $\endgroup$
    – Pondlife
    Oct 5, 2019 at 18:39

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