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During instrument training I, and many of my fellow pilot friends, were taught that the clock (as mentioned in 91.205) must be panel mounted for IFR flight. I have not been able to find verification of the panel mounted requirements. I failed to find any mention of a clock in Part 23 (Normal Category Aircraft Airwrthiness) and in Part 91 does not specifiy that it need be panel mounted. 

That being said, since many aircraft that are certified for IFR flight come with a clok in the aircraft, and it is on the airworthiness certiificate, that it must be in an operable condition. 

The only mention I can fid on the high-tech FAR search database, google.com, is an AOPA aritcle that referenced a 1981 Legal Interpretation for a pilot that was flying a Part 135 operation without a clock. However, I can not find the original Legal Interpretation from the FAA, just the copy and pasted portion on the blog post. The other issue is that it pertains to Part 135, not Part 91 operators. 



Does anybody have any knoweldge of regualtions or a document with the FAA stamp on it providing for a regulation that the clock must be panel mounted?





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8 Answers

  1. Kris Kortokrax on Mar 16, 2014

    Following is the pertinent text from the legal interpretation. The regulatory references are different today because the regulations have been recodified.

    April 23, 1981
    Mr. Nicholas A. Castruccio

    Dear Mr. Castruccio:
    This is in reply to your October 6, 1980, request for an interpretation of Section 135.179 of the Federal Aviation Regulations (FAR). You presented three questions for our resolution which, with our answers, are as follows:

    1. The aircraft is airworthy except the clock installed in the cockpit is inoperable. Would flight be allowed under Section 135.179 if there were no MEL and if the pilot in command possesses a reliable operating watch on his person? If so, who has authority to release the flight?

    If the aircraft is type certificated for instrument flight rules, a clock is required by Section 91.33(d). However, even if the aircraft is not type certificated for instrument operations, other requirements apply.
    Section 21.181 provides in pertinent part that an airworthiness certificate is effective so long as the maintenance, preventative maintenance, and inspections are preformed in accordance with Parts 43 and 91. Section 91.27(a)(1) provides in pertinent part that no person may operate an aircraft unless it has within it a current airworthiness certificate. Section 91.165 provides in pertinent part that no person may operate a civil aircraft unless it is in an airworthy condition, and that between inspections, defects in the aircraft must be repaired as prescribed in Part 43. Thus, to maintain the validity of the airworthiness certificate without a change to the type certificate, the clock must be operating for all operations, and operations with the clock inoperative would violate Sections 91.165, 135.3, and 135.143(a). A wristwatch would not substitute for the clock. The MEL and the letter of authorization for its use under Section 135.179(b) constitute a supplemental type certificate and provide a way to operate with the clock inoperative if the MEL so authorizes.

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  2. Chris Carlson on Mar 16, 2014

    Thank you Kris

    Could you provide the link to that interpretation link?

    The link I posted in the question has the same interpretation, but I could not find that interpretation on the FAA website.

    That interpretation seems to be more about having all intruments in the airworthiness certifcation working, than the regulatory requirment for the clock to be panel mounted. The airworthiness regulations (part 23) do not mention a clock being panel mounted, however 91 indicates the need for a clock. Could an aircraft be airwrothy certifed for IFR flight without a clock?

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  3. Kris Kortokrax on Mar 16, 2014

    I looked at several MELs (Generic single engine, Pilatus PC-12, KingAir 200, Cessna 310 and several jets). The jets I looked at contain no relief for the clock. The others only allow for VFR operations if the clock is inoperative.

    There is no link for the interpretation. I cut and pasted from information on a CD to which I subscribe.

    The requirement probably comes from the wording in 91.205(a) which states “unless that aircraft contains the instruments and equipment”.

    In the same way that I cannot take my Boy Scout compass aboard to substitute for an installed compass, I cannot wear my wrist watch or place a wind up alarm clock on top of the panel to substitute for an installed clock.

    See AC 20-94A which was issued in 2007 and allows for use of a digital clock instead of a clock with a sweep second hand.

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  4. Chris Carlson on Mar 16, 2014

    Frustrating, but acceptable. The extent of the regulation is derived in that 91.205 states “aircraft contains” and that it must be a certified FAA clock, which in essence would be a panel mounted clock. If a clock is in the airworthiness certificate, it is obviously needed to be operable (as per 21.181)

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  5. Sam Dawson on Mar 16, 2014

    Also from Administrator v. HAMMERSTRAND.
    “2. Absence of an installed clock. The Administrator charged
    that respondent operated the aircraft under IFR when he did not
    have the required clock installed in the instrument panel. The
    law judge agreed, rejecting respondent’s arguments that a
    passenger had a watch with the same required functions (hours,
    minutes, and seconds), another instrument in the aircraft could
    substitute for the clock, and the weather was VFR.

    Respondent continues to ignore, however, the fact that the
    regulation requires the installed clock whenever IFR operations
    are conducted, and the record demonstrates that respondent
    obtained and used an IFR clearance when he left Gillespie Field.
    Whether respondent actually needed such a
    clearance is immaterial to the §§ 91.33(a) and 91.165 violations,
    as are the weather conditions at the time.7
    Moreover, there is unrebutted evidence that the absence of the clock made the aircraft unairworthy in violation of § 91.29.”

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  6. Chris Carlson on Mar 16, 2014

    thank you same.

    another case of a grey area becoming black and white within the pen of a judge

    I’ll let my OCD down, and just accept it

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  7. Chris Carlson on Mar 16, 2014


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  8. Sam Dawson on Mar 16, 2014

    Note, a working clock must be installed. You don’t have to use it.

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