If I am on the sid I will maintain the initial block altitude untill the specified dme point and then climb in accordance with the published sid,even though i cannot get in on the RT,unless i receive the instruction Maintain. Any controllers have a problem with that.
Well, I'm not a controller but I don't believe that's what you should do.
First, let's hit the "cannot get through on the RT" bit on the head. If you're in doubt,
of course you're going to ask if you can. But the whole point of having clearances is that they provide a plan of action if you cannot communicate further with RT. It's absolutely vital that the clearance is unambiguous in the
absence of further instructions or clarification.
My understanding is that a level instruction issued by the controller is an amended clearance that cancels the vertical profile of any previous clearance, including the SID. MATS Pt 1 Section 1 Ch 5 para 6.2 makes that explicit. But I cannot for the life of me find any reference to that in regulatory material that the pilot conventionally has access to -- Annex 2, PANS-OPS, PANS-RAC, UK AIP.
If the controller expects you to resume the SID, they'll need to use a phraseology similar to eyeinthesky's suggestion: "Climb to altitude 4000ft, further with the SID". Actually I don't like that much. At what precise point am I released from the 4000 ft restriction, particularly if there isn't a 4000 ft step in the SID?
Given the emphasis on level busts over the last few years, I'm amazed that there is such a gulf of ambiguity here.
