Dave Butler wrote:

Some good guesses, but I think I can suggest some better ones...


ATC is not going to assign holds to two aircraft at the same holding point at
the same altitude. So unless "improper entry" includes an altitude bust, I don't
think this is a problem.

I'll give you something better than guesses. Controllers working traffic don't
care, perhaps, but their managers do. There are holding patterns in the New York
and Washington Center areas that are so close to each other, that speed is limited
to 200 knots above 6,000 to keep the patterns from overlapping. Improper entires,
at least in jets, could cause an aircraft to go into the other pattern's airspace.
This was demonstrated in holding pattern criteria meetings. Radar doesn't help,
because radar service is usually terminated in these busy patterns due to multiple
merging targets.




The proper entry makes it so that ATC can anticipate / predict your next
move, knowing how the entry to the hold from your direction of travel.

I don't think ATC can see well enough (or cares) what kind of entry you perform.


That's right, they can't see well enough to help out in conjested airspace.



Just like working in the pattern at an uncontrolled airport, you would
want people to enter the pattern appropriately to keep things neat and
orderly.

Don't want some one doing a right hand pattern at a left hand pattern
airport....

I think a better answer is that doing the prescribed entry gives you the most
margin for error while keeping you inside protected airspace. If you're buzzing
around in a C172, your turn radius is tight and there's plenty of protected
airspace, and you can screw up the entry big-time and still stay protected. If
you're flying at the limits of holding airspeed, and the wind is blowing, and
you're a little sloppy with your navigation, and you do the wrong entry, it may
put you outside protected airspace.

In a Cessna 172, no doubt about it. But, the instrument rating is not a rating ride
limited to 172's.