Figure 2-42. Changeover points.  if the distance between two facilities is over 102 NM and the  COP is placed at the midpoint, the system accuracy lines  extend beyond the minimum widths of 8 and 12 NM, and a  flare or spreading outward results at the COP. [Figure 2-43]  Offset COP and dogleg segments on airways or routes can  also result in a flare at the COP.  behind. These COPs divide an airway or route segment and  ensure continuous reception of navigation signals at the  prescribed minimum en route IFR altitude. They also ensure  that other aircraft operating within the same portion of  an airway or route segment receive consistent azimuth  signals from the same navigation facilities regardless of  the direction of flight.  Direct route flights are flights that are not flown on the  radials or courses of established airways or routes. Direct  route flights must be defined by indicating the radio fixes  over which the flight passes. Fixes selected to define the  route should be those over which the position of the aircraft  can be accurately determined. Such fixes automatically  become compulsory reporting points for the flight, unless  advised otherwise by ATC. Only those NAVAIDs established  Where signal coverage from two VORs overlaps at the MEA,  the COP normally is designated at the midpoint. Where  radio frequency interference or other navigation signal  problems exist, the COP is placed at the optimum location,  taking into consideration the signal strength, alignment  error, or any other known condition that affects reception.  The COP has an effect on the primary and secondary  obstacle clearance areas. On long airway or route segments,  Direct Route Flights  Figure 2-43. Changeover point effect on long airway or route segment.  2-21  13,000 ft  13,000  22  45  V344  4.5°  6.7°  4.5°  6.7° 70  70  4 NM  4 NM  Secondary areas  Primary areas  V214  2 NM  2 NM  Flare  Flare 