a pilot is unable to maintain a descent rate of at least 500 fpm,  advise ATC. Also advise ATC if it is necessary to level off  at an intermediate altitude during descent. An exception to  this is when leveling off at 10,000 feet mean sea level (MSL)  on descent or 2,500 feet above airport elevation (prior to  entering a Class B, Class C, or Class D surface area) when  required for speed reduction. Standard Terminal Arrival Routes (STARs) (as described  in Chapter 1) have been established to simplify clearance  delivery procedures for arriving aircraft at certain areas  having high density traffic. A STAR serves a purpose  parallel to that of a DP for departing traffic.  [Figure 10-3] Standard Terminal Arrival Routes (STARs) SC-4,16DEC2010to13JAN2011 SC-4,16DEC2010to13JAN2011 Figure 10-3 .  Standard terminal arrival route (STAR). 10-9