The airport grade verification procedure on AIP-funded projects is more demanding than highway or commercial site work — tighter tolerances, mandatory inspector sign-offs between lifts, and strict instrument requirements. This guide walks through the complete field procedure from control setup through inspector sign-off and documentation.
What is the procedure for airport grade verification?
Set control from certified survey monuments, shoot grades at stations not exceeding 50 feet across the full pavement width, compare each shot to the approved design, document deviations, get inspector sign-off before placing next lift. Total stations or RTK GPS are acceptable equipment; both must be calibrated.
Before beginning any grade verification work on an AIP airport project, confirm that your surveying equipment meets the certification and calibration requirements. Using uncalibrated equipment — or equipment with an expired calibration certificate — voids the associated grade documentation and can trigger stop-work.
The calibration certificate must accompany the equipment on site and be available for inspection officer review at any time. Keep a copy in the project QC binder.
All airport grade verification control must trace back to the project's permanent survey monuments — established by the airport's licensed surveyor and documented in the project control file. These monuments are typically rebar with caps set in concrete, located off the grading area where they will not be disturbed by construction.
Total station setup: Set up over a known monument. Back-sight to a second monument to establish orientation. Confirm the back-sight closes to within ±0.01 ft of the known distance and ±5 arc-seconds of the known bearing. If the closure exceeds these limits, check for instrument setup error, monument disturbance, or instrument malfunction before proceeding.
GPS rover setup: Connect to network RTK (NTRIP) or set up a base station on a known monument. After achieving Fixed RTK lock, measure two or more additional control points as a check. Both check points must agree to within ±0.02 ft horizontally and ±0.03 ft vertically. Document the check measurements in the field log.
Never use temporary grade stakes, hub points, or lath as control for grade verification — they are set for construction use and are frequently disturbed by equipment. Always trace back to the permanent monuments even if it takes extra time.
Set up a systematic shot pattern at 50-foot intervals along the pavement centerline, with cross-section shots spanning the full pavement width. For a 150-foot-wide runway:
This pattern produces five shots per 50-foot station for a 150-foot-wide runway. For wider runways or areas with complex cross-slope geometry (superelevated areas, drainage swales), add shots to adequately document the cross-section. The question to ask: "If an FAA inspector interpolated between my measurement points, would they have adequate data to confirm grade at any point in this area?" If not, add more shots.
Record each shot with: station number, offset (L or R distance from centerline), measured elevation, design elevation from the project plans at that station and offset, and deviation (measured minus design). Flag any point where the deviation exceeds the applicable tolerance (±0.04 ft for runway subgrade, ±0.03 ft for taxiway subgrade).
Design elevations come from the approved project plans — specifically the earthwork plan and profile sheets, which specify the design grade at each station and offset. Confirm you are using the current approved revision of the plans, not an earlier design issue. Design changes occur on airport projects, and using superseded plan sheets is a common source of false grade failures.
When a deviation exceeds tolerance, the point is a non-conformance. Document it immediately:
After the grading crew corrects the high or low area, re-shoot the affected stations. The corrective action record must include:
Do not re-shoot only the previously failed points — re-shoot the full 50-foot station cross-section including the previously passing adjacent points. It is common for grading corrections to create new deviations at adjacent points.
Once all points in the lift are within tolerance and all non-conformances are resolved, compile the grade documentation package for the lift and present it to the airport inspector (resident project representative). The package should include: the measurement summary for every station (all points within tolerance), the corrective action records for any originally failed points, and the field QC inspector's certification signature.
The inspector reviews the package and — if satisfied — signs the daily inspection report indicating that the lift has been verified and approved for the next phase. This sign-off is mandatory before any material is placed on the lift. Document the inspector's sign-off date and time.
For more on the full QC documentation system that sign-off feeds into, see the airport pavement QC documentation requirements guide. The Sitemark airport platform manages this entire workflow digitally — from field measurement through inspector sign-off to QC binder assembly.
Sitemark captures grade shots at 50-foot stations, flags non-conformances in real time, and routes inspector sign-off requests digitally — eliminating the paper QC binder assembly step at closeout.
Start Free Trial →Download AC 150/5370-10 and related airport construction advisory circulars from the FAA.
FAA Airports →Yes, RTK GPS rovers with Fixed RTK solution accuracy of ±0.01 ft vertical are acceptable. They require the same calibration documentation as total stations, plus control point checks at setup and each shift. Some airports require cross-checking GPS against total station measurements at project start.
A missing station is a documentation non-conformance. If discovered during an FAA oversight visit after the lift is covered, you may be required to demonstrate compliance through cores or probes — expensive and disruptive. Missing stations discovered during review will require explanations and may require additional field investigation.
Document it accurately with the actual deviation. If it is within tolerance, it passes — document it as a close-tolerance pass. If it exceeds tolerance, even by 0.001 ft, it is a non-conformance. Never round measurements to avoid documenting a failure — falsifying QC records has serious consequences.