IFR Flights

[ranga]

Is there a regulation in FAA that insists on having both sides ASI (i.e. both pilot and copilot's) instrument displaying airspeed indication available for the flight to continue Instrument Approach and land? In other words can I go and land off, say an ILS approach if either pilot's or copilot's Air Speed Indicator(ASI) is not available and the visibilty is only suitable for say CAT-I ILS only?

[GlueBall]

My Cessna was IFR certified without a copilot's instrument panel.
If you are talking about transport category jets, one ASI failure inflight would not preclude you from continuing a flight and conducting an instrument approach at destination.

[westhawk]

Ranga,

I am not aware of any US FAR that specifically addresses the situation you describe. Barring any limitations contained in the company operations manual or flight manual, it would be up to the PIC to determine the most prudent course of action to take under the prevailing circumstances. Cat II ops have their own requirements for redundancy and do not apply to cat I ops. A couple of questions would be in order before proceeding. What level of confidence do you have in the remaining ASI? Is the circumstance that caused the first failure likely to affect the other ASI(s)? What other indications are available to cross-check the accuracy of the remaining ASI such as stby ASI or AOA indicator/indexer? With either of these available, and using normal thrust settings, attitude and configuration, I don't see any problem continuing the approach to a non-critical length runway. Same for the missed approach, if required. ATC should be informed of the failure and any required assistance requested. Of course, once on the ground, the legality of the next takeoff would depend on the availability of MEL relief, if not repaired. Even if available, the MEL may require operational limitations or prohibitions against entering certain weather conditions. All of these considerations depend greatly upon the specific aircraft and company procedures. There may be no single right answer to your question unless talking about a particular aircraft operating on a particular company certificate. At my company and in my aircraft, I would fly the approach normally with my usual AOA crosscheck. It would have to be repaired before the next flight, as there is no relief for this system in our MEL.

I stand ready to accept correction from anyone who can quote a controlling US regulation or has good reason to believe my analysis to be incorrect in any respect. Always ready to learn something new. Hope this helps.

Best regards,

Westhawk

[Intruder]

The applicability of the MEL ends at V1 (or pick your definition of "takeoff"). After that, an equipment failure is handled according to the approved checklist. If there are no written restrictions, you can proceed as filed and shoot any required approach.

Most commonly there is a more restrictive equipment list for Cat II and Cat III ops. If you have a failure before DH or AH that brings the aircraft below the minimum requirements, you are obligated to go missed approach. As always, if there are other extenuating circumstances, the PIC can use his emergency authority to override those requirements.