Narrative:

After an uneventful flight we were on final approach on the ILS runway 7 (I was the pilot flying). While on glidepath and on localizer at approximately 4900 ft we encountered moderate turbulence and at the same time the autopilot suddenly disconnected; the FMA (flight mode annunciator) indicated cws (control wheel steering) for both pitch and roll; and both flight directors were lost. We were at this point in visual conditions with the runway in sight so I elected to continue the approach visually. A few seconds later we heard the 'glideslope' aural warning and realized we were indeed below the glidepath. Looking out the window; we both commented that even though we had the glideslope warning; we appeared to be high; so we continued the visual approach using visual cues and landed normally on the touchdown zone.after the flight and upon further review of all available information; I found a note on the mroc route brief that warned of the potential for optical illusion due to upward slope on runway 7. At that point I realized that due to the compounding factors (moderate turbulence; sudden loss of a/P; loss of flight director; etc.) we might have been below glidepath for a portion of the approach.I have been to [mroc] several times before (although never at night) and I can say that the illusion is much more pronounced at night time.in my opinion; the note should be added to the airport information page under the arrival notes.

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Original NASA ASRS Text

Title: B737-700 flight crew reported they descended below the glideslope on approach to MROC airport; runway slope was cited as contributing to the optical illusion.

Narrative: After an uneventful flight we were on final approach on the ILS Runway 7 (I was the Pilot Flying). While on glidepath and on localizer at approximately 4900 ft we encountered moderate turbulence and at the same time the autopilot suddenly disconnected; the FMA (Flight Mode Annunciator) indicated CWS (Control Wheel Steering) for both pitch and roll; and both Flight Directors were lost. We were at this point in visual conditions with the runway in sight so I elected to continue the approach visually. A few seconds later we heard the 'Glideslope' aural warning and realized we were indeed below the glidepath. Looking out the window; we both commented that even though we had the glideslope warning; we appeared to be high; so we continued the visual approach using visual cues and landed normally on the touchdown zone.After the flight and upon further review of all available information; I found a note on the MROC route brief that warned of the potential for optical illusion due to upward slope on Runway 7. At that point I realized that due to the compounding factors (moderate turbulence; sudden loss of A/P; loss of Flight Director; etc.) we might have been below glidepath for a portion of the approach.I have been to [MROC] several times before (although never at night) and I can say that the illusion is much more pronounced at night time.In my opinion; the note should be added to the airport information page under the arrival notes.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.