Part 121 Reg question

[skipro101]

Going to Horizon Air interview but have a part 91 background. They ask 121 questions. I am hoping someone on here could help me out with some questions and answers that i typed up. The questions are in back, answers in blue.

1) Are my blue answers correct?
2) Anyone have answers for the ones that arent answered?

What are Part 121 landing minimums?
What are Part 121 take off minimums? 1sm if 2 engines or less. 1/2sm if 3 or more. Or, alternate take off minimums if published.
When do you need a takeoff alternate (121)?
When the weather is below the minimums specified in the operations specifications, you need an alternate.
What are the alternate airport requirements (121)?
If a/c has 2 engines: Alternate must be within 1 hour at normal cruising speed in still air with one engine inop.
When do you need a destination alternate (121)?



Thanks a bundle!

 

[skipro101]

Actually, I think I might know the destination alternate. Is this correct?......

1-2-3 rule, and if you need an alternate and the alternate wx forcast for time of arrival at alternate is marginal, you need a second alternate.

Sound right?

 

[Doc Holiday]

Landing mins: They are what the certificate holder is authorized for. CAT 1 minimums are 1800 RVR or 1/2sm. No visibility values below 1/2sm may be used even though 1800 RVR equates to less than 1/2sm.

Takeoff mins: You are correct until the last part. Those are referred to as "lower than standard" and only apply if the operator is authorized to use them.

Takeoff alternate: You are on the right track. A takeoff alternate is required when the weather at the airport of departure is below the lowest authorized landing minimums.

Alternate airport: Your answer is correct for a takeoff alternate. For takeoff, first and second destination alternates there is a formula in the opspecs for deriving the weather required for designating an alternate.

Destination alternate required: For a 121 operator is most likely the 1-2-3 rule.

Hope this helps, hope your interview goes well.

 

[Carl_Spackler]

For Landing it the most restrctive of published mins, aircrew mins (eg. high mins ca), or aircraft.

For example if the approach mins are 1800 rvr, but the CA is on high mins, you would be limited to the CA.

If you were trying to do a CATII or III and there was an inop radar altimeter, you could only go to the approach mins for CATI.


As Doc said the 1hr/still air/1 engine inop is for a T/O alternate. To determine if that, or any alternate is legal you have to apply the formula. For most airlines it's 200 & 1/2 or 400 & 1. If you have 2 approaches to seperate runways using seperate nav-aids you add 200ft to the higher of the MDA/DA's and 1/2 mile vis to the higher of the 2 vis mins. In this case runway 18/36 are considered seperate runways eventhough they are on the same piece of concrete. Also a localizer that serves two runways is a seperate nav aid if the identifiers are different.

If you use one approach then you add 400 to the MDA/DA and 1 mile to the visibility.

good luck with the interview.

 

[A Squared]

Destination alternate required: For a 121 operator is most likely the 1-2-3 rule.

Hope this helps, hope your interview goes well.

Careful with this one. Make sure you know what kind of 121 operation it is. The answer varies depending on what type of operation.

 

[ackattacker]

Takeoff mins need clarification...

Generally "lower than standard" takeoff mins are approved in the ops specs unless the published takeoff mins for the runway are higher than standard, in which case the published mins apply. Clear? Most 121 operators can takeoff with RVR values as low as 600, if the runway has the proper lighting and number of RVR transmissometers.

All of these "121" questions are tricky because the answers are often in the operation specifications, instead of the regulations. And ops specs sometimes vary from operator to operator.

 

[bobs98tlr]

I know this is an old post, i did a search and was curious about something.

At a 121 company, obviously the ops specs and published mins, current weather are controlling. However for an interview. As for the many of us I want to get this answer right (all the other ones too). When asked about 121 t/o mins. Should i answer as follows...

Standard is 1 mile vis for 2 engines and 1/2 mile for 3+ engines. However if the ops spec have lower than standard take off mins we can use those based on the published mins, current weather and the equipment oporating (RVR, CL, RCLM, ect..)?

I know i have the regs down im just not exaclty clear on how they want the question asked. Thanks.

 

[A Squared]

I know this is an old post, i did a search and was curious about something.

At a 121 company, obviously the ops specs and published mins, current weather are controlling. However for an interview. As for the many of us I want to get this answer right (all the other ones too). When asked about 121 t/o mins. Should i answer as follows...

Standard is 1 mile vis for 2 engines and 1/2 mile for 3+ engines. However if the ops spec have lower than standard take off mins we can use those based on the published mins, current weather and the equipment oporating (RVR, CL, RCLM, ect..)?

I know i have the regs down im just not exaclty clear on how they want the question asked. Thanks.

The way I would answer the question in an interview is like this:

Standard Takeoff minimums are XXXXXXX but individual Ops Specs may allow for lower takeoff minimums. Period. You've answered the question

If they want to get into what must be operating or not in regards to RVR, lights, let them ask.

 

[bobs98tlr]

Even better, thanks for the quick response.

 

[dispatchguy]

121 Destination Alternate - 1-2-3 rule.

2nd Destination Alternate, if you are being 3585'ed (dont worry about that one, until youre in class), or when the weather is marginal. Marginal is defined by the operator. My favorite question when giving a dispatcher desk check is to ask what the FAA's definition of marginal is.