From runway surface survey to rehabilitation decision: one runway end to end

A runway rehabilitation decision rests on a chain of documents, each owning one stage and each handing a different kind of evidence to the next. The United States Federal Aviation Administration (FAA) Advisory Circular (AC) 150/5380-9 (Guidelines and Procedures for Measuring Airfield Pavement Roughness, 30 September 2009) governs the roughness survey (FAA, 2009). AC 150/5380-7B governs the pavement management programme (PMP) (FAA, 2014b), AC 150/5380-6C maintenance (FAA, 2014a), and AC 150/5370-10H construction (FAA, 2018). This guide follows one synthetic runway through them. It is engineering background, not operational guidance: the decision to operate, restrict or close a runway belongs to the aerodrome operator under its State's rules.

Key facts

• FAA Advisory Circular (AC) 150/5380-9 (30 September 2009) sets a 0.25 m survey interval for the Boeing Bump Index (BBI) and treats roughness by its effect on aircraft.
• The FAA airport pavement management programme AC is 150/5380-7B (10 October 2014), and the maintenance AC is 150/5380-6C of the same date.
• AC 150/5370-10H item 401-5.3g sets a contractor quality-control smoothness check of less than 1/4 inch in 12 feet, which is a check and not acceptance.
• AC 150/5320-12C sets out friction runs at 40 mph (65 km/h) and 60 mph (95 km/h) with a uniform 1 mm water depth, and a complete survey uses both speeds.
• UK CAP 781 (Runway Rehabilitation and Maintenance, 2nd edition, November 2025) is guidance on managing hazards during rehabilitation works, not a source of limits.
• This guide is engineering background; the decision to operate, restrict or close a runway belongs to the aerodrome operator under its State's rules.

Which document governs each stage between survey and decision?

Each stage has one owning document, and the evidence it produces is what the next stage reads. The hub guide on runway surface thresholds and the documents that set them answers what the limit is; this guide covers the order of work.

Stage	Document (edition)	Evidence produced
Survey and roughness evaluation	AC 150/5380-9 (2009)	Profile files with line offsets; exceedance list by chainage
Pavement management	AC 150/5380-7B (10 October 2014)	Condition records; option appraisal
Maintenance options	AC 150/5380-6C (10 October 2014)	Repair choice and its reasons
Friction thread	AC 150/5320-12C (18 March 1997 base text, current with Change 9, 29 May 2025, which replaces App 4 only)	Friction survey at both speeds
Design and evaluation	AC 150/5320-6G (7 June 2021)	Structural evaluation, owned elsewhere
Rehabilitation planning	UK CAP 781 (2nd edition, November 2025)	Planning case; regional comparator
Construction quality control (QC)	AC 150/5370-10H (21 December 2018)	As-built smoothness records
Re-survey	AC 150/5380-9	Same lines, same settings

Chainage is distance along the runway. Both 5380 letters named in the table replaced earlier letters, 6B and 7A, so name the letter in every record.

What does the survey stage leave behind?

The survey leaves a profile per line, and the lines are part of the data. AC 150/5380-9 sets a 0.25 m (0.82 ft) survey interval, with straightedge lengths from 0.5 m up to 120 m (394 ft), which gives 479 lengths for every point (paragraph 2.2) (FAA, 2009). Survey lines run along the centreline and at offsets either side; an offset of 3.05 m (10 ft) can address Airplane Design Group (ADG) II to III and 5.22 m (printed by the AC as 17.5 ft) can address ADG IV to VI, and the gear position need not be matched exactly (paragraph 2.2f).

The AC defines airfield roughness by its effects on the aircraft, such as fatigue, cockpit vibration and excessive vertical acceleration, not by passenger ride, and it treats texture as a separate matter (paragraphs 1.2b to 1.2g). Its scope is single bumps; FAA research (August 2024, not FAA policy) recommends adding multiple-event evaluation (FAA, 2024b).

Narrated film · 2:48

Survey to decision, end to end

A journey of eight stages shows the governing document at each hand-off, then a synthetic 3,000 m exceedance strip by chainage shows why event length understates the binned planning extent.

Read the film transcript

How does a rough patch on a runway survey become a decision to rehabilitate? Eight stages stand between the survey and the decision, and each stage is owned by one document. Advisory Circular one-fifty slash fifty-three-eighty dash nine governs the roughness survey, and the dash seven B letter governs the pavement management programme. Maintenance sits in the dash six C letter, and construction quality control in fifty-three-seventy dash ten H. This is engineering background on one synthetic runway; operating decisions belong to the operator. The survey leaves a profile per line: the centreline, and lines five point two two metres left and right. Points sit every zero point two five metres, and each point is tested against four hundred seventy-nine straightedge lengths. Now build the Boeing Bump Index at a chainage x, in metres. Try every straightedge configuration, and keep the largest ratio. In each ratio, h is the bump height at the point, in millimetres, divided by h acc of b, the acceptable limit in millimetres at bump length b. With synthetic heights and limits, the ratios are one point three, zero point six two and zero point eight eight, so the index is one point three. Above one is excessive or unacceptable, and the index alone does not say which, so it marks where to look. Run that along three thousand metres on three lines, and the synthetic bumps above one become eight events. The centreline has three, and its worst peaks at one point nine. Add the lengths: the left line totals two metres, the centreline seven point seven five, and the right line six point two five. Now the share of runway length affected, built in this order. Share equals the sum of the event lengths, each called ell i, divided by the runway length L, times one hundred percent. For the centreline, seven point seven five metres over three thousand metres is zero point two five eight percent. All lines together sum to sixteen metres, which is zero point five three three percent. The planning extent is n b, the bins holding an event on any line, times the bin width w, divided by the runway length, times one hundred percent. Five bins of one hundred metres make five hundred metres, or sixteen point seven percent of the runway. No document sets that hundred metre bin; it is a planning assumption, not a repair extent. Friction runs alongside, at forty and sixty miles per hour, over one millimetre of water. A complete survey uses both speeds. For construction, a quarter inch in twelve feet is a contractor quality control check, not acceptance. Hand-offs fail where the record omits what the next stage needs. Record line offsets, direction, tool, version and filter settings, so a re-survey repeats the same lines. Keep the profile files, exceedance list, condition records, friction speeds and as-built records. Chain the stages, keep the evidence at each one, and the decision stays with the operator.

How does a profile become an exceedance list?

A profile becomes a list through the Boeing Bump Index (BBI), the FAA's index derived from the Boeing bump criteria. For each point the software compares the bump height seen by every straightedge configuration with the acceptable limit at that bump length, and keeps the largest ratio. A BBI below 1.0 falls in the acceptable zone and above 1.0 in the excessive or unacceptable zones (paragraphs 2.3 to 2.5) (FAA, 2009). This guide does not recompute bumps; see how to find the bumps that load the landing gear.

The formula, term by term: Boeing Bump Index at a point

Equation 1: BBI(x) = max over configurations of [ h ÷ h_acc(b) ]

symbol	what it is in words	unit	where its value comes from	typical range
x	Chainage of the point	m	The 0.25 m survey grid	0 to runway length
configuration	One straightedge length (479 lengths, 0.5 to 120 m) with the point at its start, at its end or anywhere along it	n/a	Paragraphs 2.2 and 2.4	All tried
h	Bump height at the point for that configuration	mm	Computed from the profile	Synthetic here
b	Bump length: the smaller of the distance from the point to the start of the straightedge and the distance from the end of the straightedge to the point	m	Paragraph 2.2d(2)	Up to 60 m
h_acc(b)	Upper limit of the acceptable zone at bump length b	mm	The AC's curve, not reprinted	Synthetic here

Where it comes from: the AC states the steps in paragraph 2.4a. Try every straightedge configuration (the point at the start, at the end or anywhere along it), measure the bump height at the point, divide by the acceptable-zone limit for the bump length b, and keep the largest ratio (paragraphs 2.2d(1) to (2) and 2.4d(2)). The limit curve is empirical, taken from Boeing's criteria; the AC prints it (Figure 2-3), and this guide does not.

Worked numbers (synthetic heights and limits, not the AC's curve): ratios of 6.5 mm ÷ 5.0 mm = 1.30, 4.1 mm ÷ 6.6 mm = 0.62 and 11.0 mm ÷ 12.5 mm = 0.88 give BBI = max(1.30, 0.62, 0.88) = 1.30.

What it means: the single largest ratio flags the configuration that most exceeds its limit, so the exceedance list says where, not why. It stops working for repeated bumps, because it scores single events. The common misreading is "above 1.0 means close". The AC does attach consequences to its zones: in the excessive zone it calls for immediate repair with closure not required (2.3b(2)), and in the unacceptable zone it says immediate closure is warranted (2.3b(3)). A BBI above 1.0 alone does not say which applies (Figure 2-4). The AC is not mandatory except for projects funded through the Airport Improvement Program or Passenger Facility Charges (Foreword), and the operating decision belongs to the operator. Read these as the AC's zone definitions only; the clause that applies the index is paragraph 2.5.

What do the management and maintenance documents add?

AC 150/5380-7B describes a pavement management programme and its use in maintenance and rehabilitation decisions, with distress manuals attached (FAA, 2014b). It is where survey evidence meets condition history and the appraisal of options. AC 150/5380-6C sets out distress causes and repair methods, and pavement management moved out of it into 7B (FAA, 2014a). Road practice has the same hand-off; see pavement management steps from register to monitoring and the insight on network screening and project investigation.

How do friction and texture run alongside?

Friction is a parallel thread, not a step. AC 150/5320-12C sets out continuous friction measuring equipment (CFME) runs at 40 mph (65 km/h) and 60 mph (95 km/h) with a uniform 1 mm (0.04 in) water depth, and a complete survey uses both speeds (paragraphs 3-16 and 3-17) (FAA, 1997). Table 3-2 gives three friction levels (new design, maintenance planning and minimum) at paragraph 3-19; see the hub rather than a copy here. Texture and friction are not the same measurement; see macrotexture vs microtexture.

How do design, CAP 781 and construction QC close the loop?

AC 150/5320-6G owns pavement design and evaluation (FAA, 2021a); thickness design is outside this guide. The UK Civil Aviation Authority's CAP 781 (Runway Rehabilitation and Maintenance, 2nd edition, November 2025, published on the CAA page on 2 December 2025) is guidance on managing hazards during rehabilitation works, not a source of limits or a way to choose between maintenance and rehabilitation; Chapter 2 (page 13) and Chapter 9 (page 24) cover runway ramping and friction (UK CAA, 2025b).

For construction, AC 150/5370-10H item 401-5.3g sets contractor QC smoothness variances of less than 1/4 inch in 12 feet (6.35 mm in 3.66 m). That is a contractor QC check, not acceptance (FAA, 2018). AC 150/5380-9 paragraph 2.3b(1) gives 0.25 in in 16 ft (printed as 0.64 cm in 4.8 m) from the AC 150/5370-10 then current, and expects new or rehabilitated pavement to fall in the lower acceptable region, so name the edition with the figure.

What does a worked example of one runway show?

Synthetic example. Every value below is generated. A 3,000 m runway is surveyed on three lines at 0.25 m, 12,001 points each, at the centreline (C) and 5.22 m left (L) and right (R) (the AC's offset for ADG IV to VI). Each point carries a synthetic BBI; points above 1.0 are thresholded, contiguous points merge into one event, and each point stands for 0.25 m. calc/exceedance_strip.py prints the result.

Eight events result. Line L has 2 events totalling 2.00 m, 0.067 % of runway length; line C has 3, totalling 7.75 m, 0.258 %; line R has 3, totalling 6.25 m, 0.208 %. The strip shows 100 m bins; # marks an exceedance:

ruler     |    +    |    +    |    +       (| every 1,000 m, + every 500 m)
line L    ....#.............#...........
line C    ....#.......#.............#...
line R    ............#.............##..
any line  ....#.......#.....#.......##..

The formula, term by term: share of runway length affected

Equation 2: share = Σ ℓᵢ ÷ L_runway × 100 %

symbol	what it is in words	unit	where its value comes from	typical range
ℓᵢ	Length of event i	m	Points above 1.0 × 0.25 m	Synthetic
L_runway	Runway length	m	Survey record	3,000 m here

Where it comes from: a plain ratio; no document sets it.

Worked numbers: line C gives 7.75 m ÷ 3,000 m × 100 % = 0.258 %. All lines sum to 16.00 m, 0.533 %.

What it means: how much pavement exceeds, line by line. It is not a planning extent.

The formula, term by term: binned planning extent

Equation 3: extent = n_b × w ÷ L_runway × 100 %

symbol	what it is in words	unit	where its value comes from	typical range
n_b	Bins holding an event on any line	count	The strip	5 here
w	Bin width	m	An assumption of this guide	100 m
L_runway	Runway length	m	Survey record	3,000 m here

Where it comes from: bins times width, over runway length; the 100 m bin is an assumed planning unit, set by no document.

Worked numbers: five bins make 5 × 100 m = 500 m, 500 m ÷ 3,000 m × 100 % = 16.7 %.

What it means: events are short, yet the binned planning extent (500 m under an assumed 100 m bin, not a repair extent) is far longer, so the share of event length understates it. It stops working where the bin rule is not the engineer's own.

Where do the hand-offs fail?

Hand-offs fail where the record omits what the next stage needs:

• Lines not recorded. Without the offset and direction, a re-survey cannot repeat the lines.
• Filter settings unknown. ProFAA, as described in the 2009 AC, accepts a single profile at 25 mm spacing, applies a sixth-order Butterworth low-pass at 2 cycles/m and resamples to 0.25 m (paragraph 3.2) (FAA, 2009). The AC's wording of "every fourth sample" cannot be right for a 25 mm input (4 × 25 mm = 100 mm), so it is not repeated here. Later ProFAA versions may differ. Record the tool, version and settings.
• BBI read as "above 1 = close". The zones are in the AC; the operating decision is the operator's.
• QC tolerance mis-cited. The 12 ft check is not acceptance.
• Friction at one speed only. A complete survey uses both.

What should be kept at each stage?

Evidence this stage produces, kept for each:

• Survey: the profile files, line offsets, direction, date, instrument, software and filter settings.
• Evaluation: the exceedance list by chainage, with peak BBI per event.
• Management: the condition records and option appraisal, with the letter named for each document.
• Friction: speeds, water depth and device for every run.
• Construction: the as-built smoothness and texture records, with the check named.
• Re-survey: the same lines and settings as the first.

Which manual governs each stage

Stages of the journey, the manual that governs each one, and the evidence each stage should leave behind.

Stage	Governing manual	Evidence this stage produces
1. Survey and roughness evaluation	FAA AC 150/5380-9	Profile files with line offsets, filter settings and the BBI exceedance list by chainage.
2. Pavement management programme	FAA AC 150/5380-7B	Condition records and the option appraisal, naming the document letter.
3. Maintenance options	FAA AC 150/5380-6C	The repair choice and the reasons for it.
4. Friction survey	FAA AC 150/5320-12C	Friction runs at both speeds with a uniform 1 mm water depth.
5. Design and evaluation	FAA AC 150/5320-6G	The structural evaluation owned by the design document.
6. Rehabilitation planning	UK CAP 781	The planning case, with CAP 781 as the regional comparator.
7. Construction quality control	FAA AC 150/5370-10H	As-built smoothness checks under item 401-5.3g, named as checks.
8. Re-survey	FAA AC 150/5380-9	The same lines and settings, so the exceedance lists compare.

The journey, step by step

1. Record the survey lines

   Write down each line's offset from the centreline, the direction of travel and the date before leaving the runway, so a re-survey can repeat them.

2. Keep the profile files and filter settings

   Store the profile files as measured, with the software, its version and its filter settings, because the BBI depends on them.

3. List the exceedances by chainage

   Threshold the BBI series at 1.0, merge adjacent exceedance points into events and record start, end and peak for each line.

4. Enter the results in the pavement management programme

   Add the exceedance list to the condition records under AC 150/5380-7B, naming the letter of the document.

5. Appraise maintenance against rehabilitation

   Set the repair methods of AC 150/5380-6C against the extent of the exceedances and the design evaluation of AC 150/5320-6G.

6. Run the friction survey at both speeds

   Run the approved continuous friction device at 40 mph (65 km/h) and 60 mph (95 km/h) with a uniform 1 mm water depth and keep the run records.

7. Plan the rehabilitation

   Use CAP 781 as a regional comparator for planning, remembering that it is guidance and not a source of limits.

8. Keep the construction smoothness records

   File the contractor's quality-control checks under AC 150/5370-10H 401-5.3g and name the check as a check, not acceptance.

9. Re-survey on the same lines

   Repeat the survey with the same lines, interval and settings so that the new exceedance list compares with the first.

Frequently asked

Which document governs the runway roughness survey?

In the United States, the Federal Aviation Administration (FAA) Advisory Circular 150/5380-9, Guidelines and Procedures for Measuring Airfield Pavement Roughness (30 September 2009), governs it. It sets a 0.25 m survey interval and defines the Boeing Bump Index (BBI), and it defines airfield roughness by its effect on aircraft rather than on passengers. Always name the edition when citing it.

What is the difference between AC 150/5380-6C and AC 150/5380-7B?

AC 150/5380-6C (10 October 2014) sets out distress causes and repair methods for airport pavements, while AC 150/5380-7B (10 October 2014) describes the airport pavement management programme and how it supports maintenance and rehabilitation decisions. The two replaced the earlier 6B and 7A letters, so records should name the letter. Pavement management moved from the first document to the second.

Is a BBI above 1.0 a reason to close a runway?

Not by itself. AC 150/5380-9 places a BBI below 1.0 in the acceptable zone and above 1.0 in the excessive or unacceptable zones. It attaches consequences to the zones: immediate repair with closure not required for excessive (2.3b(2)), and immediate closure warranted for unacceptable (2.3b(3)). A BBI above 1.0 alone does not say which applies. The AC is not mandatory except for AIP- or PFC-funded projects, and the decision to operate, restrict or close belongs to the aerodrome operator and the rules of its State, not to this guide.

Is the 1/4 inch in 12 feet smoothness check an acceptance test?

No. AC 150/5370-10H (21 December 2018), item 401-5.3g, sets contractor quality-control smoothness variances of less than 1/4 inch in 12 feet (6.35 mm in 3.66 m), and that is a quality-control check, not acceptance. AC 150/5380-9 paragraph 2.3b(1) gives 0.25 in in 16 ft (printed as 0.64 cm in 4.8 m) from the AC 150/5370-10 then current, so the edition should always be named with the figure.

Where does friction fit in a rehabilitation decision?

Friction runs as a parallel thread. AC 150/5320-12C sets out approved continuous friction measuring equipment run at 40 mph (65 km/h) and 60 mph (95 km/h) with a uniform 1 mm (0.04 in) water depth, and a complete survey uses both speeds. The results feed the maintenance decision alongside the roughness record, and neither replaces the other.

Where this connects

Read how to survey runway roughness on the centreline and wheel paths for the first stage and AC 150/5380-9 explained for the document. The road equivalent is from visual rating to rehabilitation shortlist. Last reviewed on 3 November 2026 against the editions named above.

References

1. FAA (2009). AC 150/5380-9, Guidelines and Procedures for Measuring Airfield Pavement Roughness. 30 Sep 2009, no revision letter, Active. Original source.Foreword; para 1.2b-g; para 2; 2.1; 2.2a-g; 2.3a-b; 2.4a-d; 2.5a-b; Fig 2-3; Fig 2-4; Ch 3 (3.1, 3.2)
2. FAA (2014b). AC 150/5380-7B, Airport Pavement Management Program (PMP). 10 Oct 2014, Active (cancels 7A); asphalt and concrete distress manuals attached. Original source.Edition and scope per the FAA document page; no paragraph cited in this guide
3. FAA (2014a). AC 150/5380-6C, Guidelines and Procedures for Maintenance of Airport Pavements. 10 Oct 2014, Active (cancels 6B). Original source.Edition and scope per the FAA document page; no paragraph cited in this guide
4. FAA (2021a). AC 150/5320-6G, Airport Pavement Design and Evaluation. 7 Jun 2021, Active. Original source.Edition and scope per the FAA document page; no paragraph cited in this guide
5. FAA (2018). AC 150/5370-10H, Standard Specifications for Construction of Airports. 21 Dec 2018, Active; errata 19 Aug 2020 (draft 10J not final). Original source.401-5.3g (p. 280); 401-6.2d; 401-6.2e; 401-8.1d; 501-4.12; 501-5.3g; 501-6.6b(4)
6. UK CAA (2025b). CAP 781, Runway Rehabilitation and Maintenance. 2nd edition, November 2025 (CAA page version date 02 Dec 2025). Original source.Ch 2 ramping p. 13; Ch 8 TTURL p. 23; Ch 9 friction p. 24; Ch 10 p. 27
7. FAA (1997). AC 150/5320-12C, Measurement, Construction, and Maintenance of Skid Resistant Airport Pavement Surfaces. Base 18 Mar 1997; Change 9 dated 29 May 2025 (replaces App 4); Active. Original source.2-2; 2-15 to 2-22; 3-3 and Table 3-1; 3-16; 3-17; 3-19 and Table 3-2; App 4 (cite from 150-5320-12c-chg9.pdf)
8. FAA (2024b). Airport Pavement Multiple-Event Roughness Detection and Evaluation, DOT/FAA/TC-24/14 (T. Gerardi, M. Gerardi). Final Report, August 2024 (does not constitute FAA policy). Original source.Exec summary; Sec 2.2, 2.3, 3.2, 3.3; 5.1.1-5.1.3; acronym list

Use the manual edition and project requirements that apply to your work. Worked examples use synthetic values and are not site-specific design advice.