There are 3 types of doors avaialable for the ERJ. the standard plug or standard stair are even-price from the factory. The question of which type a carrier wants is specific to their operating practices. Chautauqua''s USAir and AmericanConnection planes are plug doors, while our America West and Delta planes are stair-type. US, AC, and HP use RJ-compatable jetways some places and ramp-level boarding others. Delta uses ramp-level (read outside) boarding in most RJ markets.
1. Standard stair-door. this is the standard swing down door with fixed handrails. It is actually the same door as on the EMB-120 prop. Many planes are also finished with provision for the plug-type door, or have been converted. This door type cannot directly mate with standard jetways due to the fixed handrail, however there are two solutions. Many stations (like F-gates in PHL) have had RJ-specific jetways installed which have a notch in the floor to accomadate the handrails. This arrangement also makes the jetway DASH-8 compatible. Alternately, and much more simply, a 5 foot long adapter bridge can be used. This is like a ship gangway. It''s narrow enough to fit between the handrails and allows mating with a standard jetway. The advantage of the standard door is that a stair platform is not required for stations that board from ramp-level.
2. Plug-type door. this like a standard airliner door. The door translates (slides as opposed to swinging) forward on opening, similar to the A-320. It is completely jetway compatible. Some stations still prefer to use an adapter bridge so that the jetway stays a foot or so from the plane, due to the risk of hitting the pitot probe with the jetway floor. The disadvantage is that a custom stair platform is needed to ramp-level board. Standard mobile stairs are too tall, a special ERJ 6-step platform is required.
3. Collapsable stairs. There is a version available that is the stair door with collapsable handrails like a CRJ, which is jetway or rampside compatable. Jetway use still requires the short adapter due to the door extending down and out from the plane, but is easier than the fixed handrails. To my knowledge, nobody has ordered this option in the US.
Following is a breakdown of the U.S. ERJ operators and types of doors:
ExpressJet: All plug-type.
Eagle: All plug-type.
Chautauqua: USAir 23 plug, 3 stair (Planes originally for TWE). AmericanConnection plug. HPE/DLC stair type.
Mesa: All plug-type.
Trans States: All stair-type.
For those looking toward the future, the ERJ-170 has a standard plug-type door with an under-floor stair, similar to the arrangement on DC-9''s and 737''s with stairs.