Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 208; Flight Crew Type 4000
Distraction; Human-Machine Interface; Confusion; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Flight Deck / Cabin / Aircraft Event Other / Unknown
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Chart Or Publication; Procedure
Flying the ENDEE THREE RNAV Arrival 4R Transition into KMDW. Received ATC clearance to 'Descend via the ENDEE 3 Arrival.' ATIS advertising approaches to 4R. Jeppesen chart for the arrival has a confusing note associated with the final point on the arrival; the BANER waypoint. The altitude at BANER is listed as 'At or above 5;000 feet.' However; there is also a note associated with the BANER waypoint that states; 'On assigned instrument approach procedure or RADAR vectors to final approach course.' After receiving the clearance to descend via the arrival; I understood our clearance to be only down to 6;000 feet as listed at the ALQUE waypoint since we were neither on an assigned instrument approach procedure or being radar vectored as stated in the note. The Captain and Pilot Flying (PF) understood our clearance to be to 5;000 feet per the altitude at BANER. When time permitted; I asked Chicago Approach Control what altitude they expected us to descend to and the response made it sound as if ATC was also unsure as to which altitude was correct. Having now asked a number of other Pilots; there is no clear consensus as to which is correct. There was no deviation because well prior to reaching any of the waypoints in question; Chicago Approach vectored us off the arrival and began assigning altitudes to us. The Controller also stated they did this routinely with aircraft on the 4R transition of the ENDEE Arrival in part due to confusion concerning the bottom altitude.While questioning ATC about what altitude they would like us to descend to can always alleviate the confusion; the procedure should be published in such a fashion as to prevent this confusion in the first place. The note at BANER is confusing and vague and doesn't provide any useful information. The note at BANER on the arrival must be changed. Removing the note completely seems to be the solution with the least chance for misunderstanding. If the intention is that aircraft remain at 6;000 feet until cleared for the ILS 4R approach; then simply remove the note since there is a 5;000A restriction at BANER listed on the approach.Conversely; if the desire is for aircraft to arrive at BANER at or above 5;000 feet even if not yet cleared for the approach; simply removing the note would again produce the desired result. Although having an at or above for the final altitude on an arrival is unusual. Until the note is changed; the only viable option is for Crews to ask ATC what altitude they are cleared to or for ATC to state the bottom altitude in the descend via clearance.
When cleared to 'descend via the ENDEE RNAV STAR to MDW; landing 4R' the flight crew of a B737 was confused as to the intent of an equivocal note at BANER; the final waypoint on that STAR/runway transition route; whether the listed 'At or above 5;000 feet' qualified as a 'bottom altitude' for their 'Descend via' clearance rather than the 'At 6;000 feet' restriction at the previous fix; ALQUE.