crossing restrictions

[N1FuelFlow]

OK just one of those grey area's. Lets take the Brandford 4 arrival in to ORD for example. Usually you are given Brandford VOR at FL240 then somwhere prior to BDF VOR they tell you to cross the Benky intersection at 11,000. My question is even though your not to BDF VOR yet can you decend below FL240 before you reach bradford. I have had other pilots I fly with say yes you can. I do not start down for Benky untill after BDF VOR to play it safe. I have seen other arrivals where this situation happens also. Any Input?

 

[PacoPollo]

OK just one of those grey area's. Lets take the Brandford 4 arrival in to ORD for example. Usually you are given Brandford VOR at FL240 then somwhere prior to BDF VOR they tell you to cross the Benky intersection at 11,000. My question is even though your not to BDF VOR yet can you decend below FL240 before you reach bradford. I have had other pilots I fly with say yes you can. I do not start down for Benky untill after BDF VOR to play it safe. I have seen other arrivals where this situation happens also. Any Input?

Yes you can start down to 11,000 prior to bradford. Now if ATC tells you to cross Bradford at FL240, expect Benkyat 11,000ft then you cant.

 

[N1FuelFlow]

sorry bad explanation. Yes they do give you cross BDF at F240 then prior to bradford they tell you cross benkey at 11,000.

 

[PacoPollo]

sorry bad explanation. Yes they do give you cross BDF at F240 then prior to bradford they tell you cross benkey at 11,000.

Well then you have to cross BDF at 240, then benky at 11,000. So you cant descend below 240 prior to BDF. Otherwise the clearance would be something like this: Cross BDF AT or Below 240 then benky at 11000.

 

[lumax]

once you receive the clearance to cross benkey at 11000, you can disregard the previous restriction at bdf. Your new clearance is benkey at 11000'

 

[501261]

once you receive the clearance to cross benkey at 11000, you can disregard the previous restriction at bdf. Your new clearance is benkey at 11000'

That's correct the new clearance is Benkey at 11,000. Think of it this way crossing the first intersection at FL240 is usually because of a MOU (Memo of Understanding) between Centers(i.e. high and low center freq's). When the low center takes the handoff you are he clears you to the lower altitude and that's all that matters now.

Think of it this way Approach Control clears you for the ILS, then the tower clears you for a visual, basically the same thing is happening here.

 

[N1FuelFlow]

Well then you have to cross BDF at 240, then benky at 11,000. So you cant descend below 240 prior to BDF. Otherwise the clearance would be something like this: Cross BDF AT or Below 240 then benky at 11000.

Paco any feed back? thats 2 to 1?

 

[172driver]

The two are correct. From Chapter 4 of the AIM:

g. The guiding principle is that the last ATC clearance has precedence over the previous ATC clearance. When the route or altitude in a previously issued clearance is amended, the controller will restate applicable altitude restrictions. If altitude to maintain is changed or restated, whether prior to departure or while airborne, and previously issued altitude restrictions are omitted, those altitude restrictions are canceled, including departure procedures and STAR altitude restrictions.

3. An arriving aircraft is cleared to the destination airport via V45 Delta VOR direct; the aircraft is cleared to cross Delta VOR at 10,000 feet, and then to maintain 6,000 feet. Prior to Delta VOR, the controller issues an amended clearance as follows: "turn right heading one eight zero for vector to runway three six I-L-S approach, maintain six thousand."

NOTE-
Because the altitude restriction "cross Delta V-O-R at 10,000 feet" was omitted from the amended clearance, it is no longer in effect.​