It depends. It is usually the most conservative of the two, but it is possible to have SPECIFIC opspecs for that specific airport that are lower than the standard mins. I would think that an airline that does this would have their jepps modified accordingly, but not sure.

Your operations specifications authorizes you to conduct an operation. In this case it is 500 RVR. However, you cannot operate below a visibility that is published on a chart.

If a published take-off minimum is greater than standard take-off minimums then you cannot depart below the published minimums.

The RWY you are on has to be 600 RVR approved. Just because your airline is certified to 600 RVR, that doesn't mean that you can go below that 800. If that were the case, we'd be doing 600 RVR T/O's everywhere we go.

So when did SLC and SEA sucede from the US? Your statement is flat out wrong. Our OpSpec, equipment, and training allow us to takeoff at these two airports down to 300/300/300. Ive done one at SEA.

FAA Approved
OpSpec: For visibility less than 600 RVR down to 300 RVR with 3
transmissometers installed, observe the following restrictions.
All the following visual aids must be available:
- Operative high intensity runway lights (HIRL),
- Operative runway centerline lights (CL), and
- Runway centerline markings (RCLM).
If all three transmissometers are operating, they are all controlling and
must be at or above 300 RVR.
If any two of the three transmissometers are operative, takeoff is
permitted if the two operative transmissometers are reporting 300
RVR or above.
Less than 600 RVR takeoff must be specifically authorized on the
Jeppesen -9A page (10-9A or equivalent).
Use HGS takeoff procedures.
The following aircraft equipment must be used:
- The HGS system
- Both Pilots’ ILS receivers
The CA must be HGS trained, qualified, and current.
The FO must be HGS trained.
The maximum crosswind is limited to 10 knots, and the maximum
headwind is limited to 25 knots.

What are the distance requirements for a takeoff alternate? Are the weather mins the same for a takeoff alternate as they are for a destination alternate, 600/2 or 800/2?

[B]
121.617 Alternate airport for departure.


(a) If the weather conditions at the airport of takeoff are below the landing minimums in the certificate holder's operations specifications for that airport, no person may dispatch or release an aircraft from that airport unless the dispatch or flight release specifies an alternate airport located within the following distances from the airport of takeoff:

(1) Aircraft having two engines. Not more than one hour from the departure airport at normal cruising speed in still air with one engine inoperative.

(2) Aircraft having three or more engines. Not more than two hours from the departure airport at normal cruising speed in still air with one engine inoperative.

(b) For the purpose of paragraph (a) of this section, the alternate airport weather conditions must meet the requirements of the certificate holder's operations specifications.

(c) No person may dispatch or release an aircraft from an airport unless he lists each required alternate airport in the dispatch or flight release.

Thanks for including the reference too!

It may depend on the the way the person is interviewing you. He may want to hear BOTH. To see if you are up on your FARs as well as your own company's OP SPECS.

The 3 separate FOM's I have worked under say that ALL alternates must comply with the same criteria.

Also, most 121 operators use a different method to determine alternate minimums. It's OP SPEC c55. Some call it method 1/method 2.

Has to deal with how many navaids/usable approaches at the alternate, etc. One says that if there are TWO approaches to add 200 ft and a 1/2 mile to both, the other says to add 400 ft and 1 mile if only using 1 approach.

The LOWEST you could ever go would be 400/1 using the method where you add 200ft and 1/2 mile, assuming you had 2 separate usable approaches that had the same published mins.

Yikes mark of the beast!