Yes, you can fly IFR without a transponder, or a clearance in Class G airspace which is not subject to ATC control. The reality is that there is very little Glass G airspace left in the continental US and where it is, flying in the “soup” (as we IFR types like to call it) is pretty dangerous.
For aircraft operating at or above FL180 (18,000 feet), you must be equipped with a Mode S-transponder-based ADS-B transmitter. For aircraft operating below 18,000 feet and within U.S. airspace, you must be equipped with either a Mode S transponder with Extended Squitter or a Universal Access Transceiver (UAT).
IFR operations in any class of controlled airspace requires that a pilot must file an IFR flight plan and receive an appropriate ATC clearance. IFR Separation. Standard IFR separation is provided to all aircraft operating under IFR in controlled airspace.
Without RAIM, GPS utilization for IFR navigation is not authorized. A minimum of five satellites are required for RAIM fault-detection capabilities, enabling a faulty satellite to be recognized and identified.
To fly IFR, pilots need an IFR-capable aircraft, a crew with Instrument Ratings that meet recency requirements, and an IFR flight plan. Flying IFR requires specialized training, equipment, and procedures that differ from those used in Visual Flight Rules (VFR).
The U.S. FAA has a pretty short list of equipment required for IFR, and GPS is not on it. In fact, all the regulation has to say about navigation equipment for standard category IFR is that it be “suitable for the route to be flown.” (14 CFR 91.205).
Your GPS display shows the lat/long distance measured between two points, and in most cases, you can use it for IFR flying. But in order to use GPS for instrument flight, you'll need a TSO-C129, TSO-C196, TSO-C145, or TSO-C146 compliant GPS (AC 20-138). The FAA refers to these as "suitable RNAV systems."
And the need for two communications radios remains obvious—what if one breaks? Gotta have a backup. Besides, with two of them you can continue to monitor ATC while you sneak off to get some weather on the other radio. Yeah, you need two of those, too.
Most of us can—and should be able to—manage without GPS or autopilot. Indeed, many pilots have flown years of safe IFR this way. But today, ATC assumes you have GPS.
It is only possible to automatically land at an airport equipped with a suitable ILS. In short, no ILS, no automatic landing.
Why Do Pilots Prefer IFR Over VFR? IFR provides pilots with greater flexibility when it comes to controlled airspace, weather conditions, and career opportunities.
Once a pilot holds a PPL, the next step is to be Instrument Rated (IR). This allows the pilot to fly IFR. Every aspect of flying is impacted by these ratings, such as flight planning, taking off, navigation, weather tracking, flight following, radar, and landing.
The harder rating to obtain out of the these two is IFR. Similar to VFR, IFR is a set of rules that govern an aircraft flying in “instrument meteorological conditions”, or IMC. IMC is defined as the type of weather that's below the minimums prescribed for flight under VFR.
There could be several reasons. One reason could be when airplanes get close to each other (perhaps they are approaching an airport). Air traffic controllers may then request pilots to turn the transponders off or to standby. Also, if the transponder is sending faulty information, the pilot might want to turn it off.
Background: In 1987, the FAA amended part 135, § 135.143(c) to require that transponders installed in aircraft conducted under part 135 must meet TSO-C112 (Mode S), if installed after January 1, 1992.
If the plane was in contact with an air traffic controller, the controller would alert the pilots that the transponder signal had been lost. But, Aimer — now head of Aero Consulting Experts — said, if they were not in contact with an air traffic controller, a pilot might miss it if the other shut down the transponder.
IFR for VFR Pilots will undoubtedly contribute to your overall flying skill, because the control techniques are just as applicable in good weather as bad. After all, the airplane doesnt know whether its flying in clouds or sunshine.
Flight Plan Requirements
All IFR flights require a flight plan submitted to an FAA facility or facilities as described in the U.S. Aeronautical Information Publication ( AIP ), Sections ENR 1.10 and ENR 1.11 and in the Aeronautical Information Manual ( AIM ), Section 5-1-6.
There's no takeoff clearance needed without a tower, but until you get the OK, the release, from approach, you can't depart IFR. So you'll then readback that clearance and they'll say “Cessna 9334H readback correct advise ready for departure.” And they may ask you which runway you're going to depart from.
All the aircraft are equipped for IFR-flights with two radio stations.
An aircraft requires a heated pitot tube ALL the time. One does not need to be in IFR weather to have water freeze in the pitot tube. Light rain, snow, even drizzle may still permit VFR flying but the condition may be enough to cause a pitot tube blockage.
A pilot experiencing two‐way radio failure at an assigned altitude of 7,000 feet is cleared along a direct route which will require a climb to a minimum IFR altitude of 9,000 feet, should climb to reach 9,000 feet at the time or place where it becomes necessary (see 14 CFR Section 91.177(b)).
While it is not legal for approaches, you can use an expired database for en route and terminal operations, as long as you verify the data is still correct, generally by reference to paper charts.
The easiest way is to read the Aircraft Flight Manual (AFM) or Aircraft Flight Manual Supplement (AFMS). If the the GPS was installed at the factory, it will be addressed in the AFM. If it was installed later via an Supplemental Type Certificate (STC), there must be an AFMS to cover the operation of the GPS.
GPS can be used in lieu of DME and ADF on all localizer-type approaches as well as VOR/DME approaches, including when charted NDB or DME transmitters are temporarily out of service. It also clarifies that IFR GPS satisfies the requirement for DME at and above Flight Level 240 specified in FAR 91.205(e).