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GPS question.

celloman

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I have a question for you all and I don't know what answer is correct.

Question: May you use a GPS for an IFR approach at any time if the data card has expired?

Answer 1: Yes, if you are using Jepp charts and you have the most up to date charts you can use them if the date on the chart is before the expiration date on the card.

Answer 2: NO!


What do you think? and WHY?
 

avbug

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Cello,

#2. No. If the database is expired, the GPS unit may not be used for approaches. The expiration date on the paper approach chart is not relevant. For the purposes of conducting an approach, an airborne GPS receiver without a current database does not meet it's certification requirements (TSO C-129). The unit is not authorized for use in approaches.

A GPS unit approved for IFR operations may be used enroute if the updatable database has expired, if the pilot can verify the accuracy of each coordinate used (each waypoint). This is acceptable for enroute use only, but not for an approach.

Additionally, a GPS may not be used to substitute for ADF/DME unless the facility being referenced is in a current airborne database.

AIM 1-1-21:

..."Equipment and Data Base Requirements

1. Authorization to fly approaches under IFR using GPS avionics systems requires that:

(a) A pilot uses GPS avionics with TSO C-129, or equivalent, authorization in class A1, B1, B3, C1, or C3; and

(b) All approach procedures to be flown must be retrievable from the current airborne navigation data base supplied by the TSO C-129 equipment manufacturer or other FAA approved source."
 

A Squared

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A little more on the "why"

One reason may be the geographical position of the waypoints. It may be discovered after an approach is published that the waypoints in the approach need to be moved a little to comply with TERPs requirements. You would not be able to tell from looking at your current approach plate that the waypoint positions are different than the "old" positions in your expired database.

Regards
 

celloman

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GPS

Thanks guys.

That is the answer we came up with at work.

The reason I was asking is on the GPS simulator it has a little quiz and this is one of the questions it asks. The answer it gives is you can use the GPS if the charts you have are 1. up to date (only with Jep) and 2. the date on the charts are before the expiration date on the GPS card.

No where could we find information in the FAR's to support this claim so I am sticking to #2

Thanks again!
 

cessna_driver2

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I found the information in the POH supplement. I had to look it up for my INST ride last weekend.
 

slapstick

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So, what if the GPS database is expired, but you wish to use the GPS for DME information on a conventional VOR approach. Can you?

Logically, you probably could, if you double checked GPS-derived info with something like a VOR crossing radial. But rules ain't always logical.

What's the consensus?
 

avbug

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According to AIM Table 1-1-8, the database must be current in order to use the GPS in lieu of ADF and/or DME.

See also AIM 1-1-21(f)(6)(c), copied below:

"Waypoints, fixes, intersections, and facility locations to be used for these operations must be retrieved from the GPS airborne database. The database must be current. If the required positions cannot be retrieved from the airborne database, the substitution of GPS for ADF and/or DME is not authorized."

It's also worth noting that if a facility upon which a DME fix is predicated is not in your database, current or not, you may not use that fix by substituting GPS for DME or ADF. For example, if the DME fix is predicated on XYZ VORTAC, and the VORTAC isn't in the database, you can't substitute the GPS for it, no matter if the database is current, or if you can still clearly identify the location of that fix.

Also worth noting is that this applies to enroute, terminal, and approach operations.
 

slapstick

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So, if I were to fly a VOR/DME approach in an aircraft without DME, but with a GPS possessing an out-of-date database, I'd identify the FAF with a crossing radial only. However, I could tune up the GPS and use the GPS-derived distance information as a "reference".


Also, if I filed airway routing, but received a clearance (GPS-equipped) direct a waypoint, then direct the destination, that waypoint becomes a complusory reporting point, correct? (AIM 5-1-12, c.)

Thanks for the clarification.
 

avbug

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Slapstick,

Most of that is correct except the last part, and the first part. When given direct a waypoint on a random RNAV route, the waypoint does not become a compulsory reporting point.

Random RNAV routes can only be approved in a radar environment. So long as in radar contact, even compulsory reporting points should not be reported without a specific request. In this case, the waypoint doesn't represent a compulsory reporting point unless this requirement is included as part of a clearance.

You stated that you could fly a VOR/DME approach without DME. This is not correct. You could substittue GPS with an approved database for DME information, but lacking this, you cannot fly a VOR/DME approach without DME, as the approach is named and predicated on this equipment. Generally an additional note is added such as "proceedure not authorized without DME."

Certainly in some cases alternate equipment may be effectively substituted and the proceedure may safely be flown. However, if you have filed without a DME indicator or an RNAV indicator, and you ever get called on the carpet, you may be required to explain how you could fly a proceedure without the equipment applicable to that proceedure in the airplane.
 

slapstick

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makes sense, avbug. also, my part about the VOR/DME appch without DME was a brainfart... i think you know what i meant anyway.

is it just me or is the AIM index in the back worthless?
 
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