GPS ENR  10  10  20  20  30  30  40  40  20  20  2  1  1  2  -7 1 50 5400  5300  5200  3900  5000  4900  4800  3600  3500  3440000  3300  3200  3100  20 80 5 100 180 170 160 150 140 130 5 154 3 NAV1 108.00 113.00 NAV2 108.00 110.60 134.000 118.000 COM1 123.800 118.000 COM2 $_{WPT }$_ _ _ _ _ _$_{ DIS }$_ _ ._ $_{NM}$ $_{DTK }$_ _ _$_{°}$ TRK 360° ALERTS  Figure 7-70.  Horizon line starts moving upward at 27 ° . Note that the blue sky remains visible at 17 °  nose-down. chevrons are positioned at 50° up on the attitude indicator.  The chevrons appear when the aircraft approaches a nose-high  attitude of 30°. The software automatically declutters the PFD  leaving only airspeed, heading, attitude, altimeter, VSI tape,  and the trend vectors. The decluttered information reappears  when the pitch attitude falls below 25°. For nose-low unusual attitudes, the chevrons are displayed  when the pitch exceeds 15° nose-down. If the pitch continues  to decrease, the unusual attitude recovery protection de- clutters the screen at 20° nose-down. The decluttered  information reappears when the pitch increases above 15°. Additionally, there are bank limits that trigger the unusual  attitude protection. If the aircraft’s bank increases beyond  60°, a continuation of the roll index occurs to indicate the  shortest direction to roll the wings back to level. At 65°, the  PFD de-clutters. All information reappears when the bank  decreases below 60°. In  Figure 7-71 , the aircraft has rolled past 60°. Observe the  white line that continues from the end of the bank index.  This line appears to indicate the shortest distance back to  wings level.  When experiencing a failure of the AHRS unit, all unusual  attitude protection is lost. The failure of the AHRS results  in the loss of all heading and attitude indications on the PFD.  In addition, all modes of the autopilot, except for roll and  altitude hold, are lost. The following picture series represents how important this  technology is in increasing situational awareness, and how  critical it is in improving safety. Figure 7-72  shows the unusual attitude protection with valid  AHRS and air data computer (ADC) inputs. The bright red  chevrons pointing down to the horizon indicate a nose-high  unusual attitude that can be easily recognized and corrected. NOTE: The red chevrons point back to the level pitch attitude.  The trend indicators show where the airspeed and altitude will  be in 6 seconds. The trend indicator on the heading indicator  shows which direction the aircraft is turning. The slip/skid  indicator clearly shows if the aircraft is coordinated. This  information helps the pilot determine which type of unusual  attitude the aircraft has taken.  Now look at  Figure 7-73 . The display shows the same  airspeed as the picture above; however, the AHRS unit has  failed. The altimeter and the VSI tape are the only clear  indications that the aircraft is in a nose-high attitude. The  one key instrument that is no longer present is the slip/skid  indicator. There is not a standby turn coordinator installed  in the aircraft for the pilot to reference. The magnetic compass indicates a heading is being  maintained; however, it is not as useful as a turn coordinator  or slip/skid indicator. 7-56