power or attitude; they should be used in conjunction with the  primary and supporting instruments in order to better manage  the flight. With the introduction of airspeed tapes, the pilot  can monitor airspeed to within one knot. Fixation can lead  to attempting to keep the airspeed to an unnecessarily tight  tolerance. There is no need to hold airspeed to within one  knot; the Instrument Rating Practical Test Standards (PTS)  allows greater latitude. Another common error associated with attitude instrument  flying is omission of an instrument from the cross-check. Due  to the high reliability of the PFD and associated components,  pilots tend to omit the stand-by instruments as well as the  magnetic compass from their scans. An additional reason  for the omission is the position of the stand-by instruments.  Pilots should continue to monitor the stand-by instruments  in order to detect failures within those systems. One of the  most commonly omitted instruments from the scan is the  slip/skid indicator. In initial training, placing emphasis on a single instrument  is very common and can become a habit if not corrected.  When the importance of a single instrument is elevated above  another, the pilot begins to rely solely on that instrument  for guidance. When rolling out of a 180° turn, the attitude  indicator, heading indicator, slip/skid indicator, and altimeter  need to be referenced. If a pilot omits the slip/skid indicator,  coordination is sacrificed. Omission Emphasis 6-28