Eliminated Immediate Access to a Solution: When is it Appropriate to 'Ascend Using' on the STAR?
Standard Terminal Arrival Procedures (STARs) play a crucial role in managing inbound IFR traffic, guiding aircraft into defined routes and streamlining the arrival process at airports. One important aspect of STARs is the "descend via" clearance, which provides pilots with a combined route and altitude clearance.
When a pilot receives a "descend via" clearance on a STAR, they are expected to descend to meet all published altitude restrictions at or before each fix, while maintaining the lateral and speed restrictions as described by the STAR. This means that pilots should:
- Maintain the published speeds and routes as per the STAR.
- Begin descending early enough so they reach the assigned or published altitude at or before the fix.
- Comply with any speed restrictions on the STAR.
- Continue the descent following the STAR vertical profile unless otherwise cleared.
The phrase "descend via" implies adhering to all lateral and vertical restrictions on the STAR and relieves ATC of the need to issue separate descent clearances to specific altitudes. This streamlines the process by combining route and altitude clearances into a single clearance that the pilot executes by following the charted STAR restrictions.
In the given scenario, an aircraft approaching Chicago O'Hare from the northwest at FL180 is cleared direct to CHDRR, descend via the MADII 7 Arrival. This means the aircraft should descend to meet the crossing restriction of CHDRR, which is 14,000', before reaching the fix. If the aircraft does not descend before reaching CHDRR, it will be 4,000' above the crossing restriction.
It is essential that the pilot monitor and adjust their descent to comply precisely with published altitude crossing restrictions at each fix along the arrival route. No specific numerical distance before the fix to start descent is mandated uniformly; rather, the pilot uses performance and wind information to ensure altitude restrictions are met by or before the fix. If ATC issues additional instructions or restrictions, those must be followed as well.
ATC is responsible for organizing arriving traffic in three ways: managing altitude, lateral path, and airspeed to keep traffic separated. They also assume responsibility for obstacle separation as long as the aircraft remains above the Minimum En route Altitudes (MEAs). The pilot is authorized to descend at their discretion to meet published restrictions and navigate laterally on a STAR.
In conclusion, the "descend via" clearance on a STAR means you descend to meet all published altitude restrictions on the arrival procedure at or prior to each fix, maintaining the lateral and speed restrictions described by the STAR. This ensures proper obstacle clearance, optimized traffic flow, and a smooth transition into the approach phase.
- When pilots receive a "descend via" clearance on a STAR, they are expected to strictly adhere to the published speeds, routes, and altitude restrictions at each fix.
- The "descend via" clearance combines both route and altitude clearances into a single clearance, relieving Air Traffic Control (ATC) of the need to issue separate descent clearances.
- Upon receiving the clearance, pilots should begin their descent early enough to meet the assigned or published altitude at or before the fix, while maintaining the lateral and speed restrictions as described by the STAR.
- In the aviation industry, ATC is responsible for organizing arriving traffic, ensuring proper altitude, lateral path, airspeed, and obstacle separation.
- Compliance with published altitude crossing restrictions at each fix along the arrival route helps maintain obstacle clearance, optimize traffic flow, and ensure a smooth transition into the approach phase.
- Pilots are authorized to descend at their discretion to meet published restrictions and navigate laterally on a STAR, but must also comply with any additional instructions or restrictions issued by ATC.
