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Appendix D Proposed Weather Factors Governing Launch Commit Criteria and Flight Rules 62

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63 Shuttle Launch Commit Criteria and Background JSC-16007 Sec. 1.4 Weather Guidelines/Rules LCC RULE: AMBIENT TEMPERATURE RESTRICTIONS A. PRIOR TO EXTERNAL TANK CRYOGENIC LOADING. PROPELLANT LOADING OF THE EXTERNAL TANK (ET) SHALL NOT BE INITIATED IF THE 24 HOUR AVERAGE TEMPERATURE FOR THE PRECEEDING 24 HOURS HAS BEEN BELOW 41 DEGREES FAHRENHEIT. B. FROM START OF ET CRYOGENIC LOADING TO LAUNCH. THE COUNTDOWN SHALL NOT BE CONTINUED NOR THE SHUTTLE LAUNCHED IF THE AMBIENT TEMPERATURE DURING THIS TIME PERIOD EXCEEDS ANY OF THE FOLLOWING CRITERIA FOR MORE THAN 30 MINUTES. (1) MAXIMUM TEMPERATURE OF 99 DEGREES FAHRENHEIT (2) MINIMUM TEMPERATURE OF 37 DEGREES FAHRENHEIT FOR WIND CONDITIONS AT OR ABOVE 5 KNOTS. (3) MINIMUM TEMPERATURE OF 47 DEGREES FAHRENHEIT FOR STEADY STATE WIND CONDITIONS BELOW 5 KNOTS. LCC RULE: PRECIPITATION CONSTRAINT THE SHUTTLE VEHICLE WILL NOT BE LAUNCHED IF: A. PRECIPITATION EXISTS IN THE FLIGHT PATH B. ICE ACCUMULATES IN ZERO-ICE OR RESTRICTED THICKNESS AREAS ON THE ET. Rationale: Thermal Tile Protection LCC RULE: SURFACE WIND LIMITS FOR LIFT-OFF (MEASURED AT 60' LEVEL) THE SHUTTLE VEHICLE WILL NOT BE LAUNCHED IF: WINDS ARE GREATER THAN: A. 22 KNOTS - STEADY STATE PRELIMINARY

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64 B. 32 KNOTS - PEAK Rationale: Design Requirement of JSC 07700 Vol X LCC RULE: NATURAL AND TRIGGERED LIGHTNING CONSTRAINTS THE LAUNCH WEATHER OFFICER MUST HAVE CLEAR AND CONVINCING EVIDENCE THAT THE FOLLOWING CONSTRAINTS ARE NOT VIOLATED. DO NOT LAUNCH IF: A. ANY TYPE OF LIGHTNING IS DETECTED WITHIN 10 NM OF THE LAUNCH SITE OR PLANNED FLIGHT PATH WITHIN 30 MINUTES PRIOR TO LAUNCH UNLESS THE METEOROLOGICAL CONDITION THAT PRODUCED THE LIGHTNING HAS MOVED MORE THAN 10 NM AWAY FROM THE LAUNCH SITE OR PLANNED FLIGHT PATH. PLANNED FLIGHT PATH: THE TRAJECTORY OF THE FLIGHT VEHICLE FROM THE LAUNCH PAD THROUGH ITS FLIGHT PROFILE UNTIL IT REACHES THE ALTITUDE OF 100,000 FEET. THE FLIGHT PATH MAY VARY PLUS OR MINUS 0.5 NAUTICAL MILES HORIZONTALLY UP TO AN ALTITUDE OF 25,000 FEET. DO NOT LAUNCH IF: B. THE PLANNED FLIGHT PATH WILL CARRY THE VEHICLE (1) THROUGH CUMULUS CLOUDS WITH TOPS HIGHER THAN THE +5 C LEVEL; OR THROUGH OR WITHIN 5 NM OF CUMULUS CLOUDS WITH TOPS HIGHER THAN THE -10 LEVEL; OR THROUGH OR WITHIN 10 NM OF CUMULUS CLOUDS WITH TOPS HIGHER THAN THE -20 C LEVEL; OR THROUGH OR WITHIN 10 NM OF THE NEAREST EDGE OF ANY CUMULONIMBUS OR THUNDERSTORM CLOUD INCLUDING ITS ASSOCIATED ANVIL CUMULONIMBUS CLOUD: ANY CONVECTIVE CLOUD WHICH EXCEEDS THE -20 DEGREE CELSIUS TEMPERATURE LEVEL ANVIL: STRATIFORM OR FIBROUS CLOUD PRODUCED BY THE UPPER LEVEL OUTFLOW FROM THE THUNDERSTORMS OR CONVECTIVE CLOUDS. ANVIL DEBRIS DOES NOT MEET THE DEFINITION IF IT IS OPTICALLY TRANSPARENT DO NOT LAUNCH IF: FOR RANGES EQUIPPED WITH A SURFACE ELECTRIC FIELD MILL NETWORK, AT ANY TIME DURING THE 15 MINUTES PRIOR TO LAUNCH TIME THE ONE MINUTE AVERAGE ABSOLUTE ELECTRIC FIELD INTENSITY AT THE GROUND EXCEEDS 1 KILOVOLT PER METER (1 KY/M) WITHIN 5 NM OF THE LAUNCH SITE UNLESS: (A) THERE ARE NO CLOUDS WITHIN 10 NM OF THE LAUNCH SITE: AND, PRO Y. l

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65 (B) SMOKE AND/OR GROUND FOG IS CLEARLY CAUSING ABNORMAL READINGS DO NOT LAUNCH I F: THE PLANNED FLIGHT PATH IS THROUGH A VERTICALLY CONTINUOUS LAYER OF CLOUDS WITH AN OVERALL DEPTH OF 4,500 FEET OR GREATER WHERE ANY PART OF THE CLOUDS ARE LOCATED BETWEEN THE ZERO (O) DEGREE AND THE MINUS 20 (-20) DEGREE CELSIUS TEMPERATURE LEVELS. E. THE PLANNED FLIGHT PATH IS THROUGH ANY CLOUD TYPES THAT EXTEND TO ALTITUDES AT OR ABOVE THE ZERO DEGREE CELSIUS LEVEL AND THAT ARE ASSOCIATED WITH DISTURBED WEATHER WITHIN 5 NM OF THE FLIGHT PATH DISTURBED WEATHER: ANY METEOROLOGICAL PHENOMENON THAT IS PRODUCING MODERATE OR GREATER PRECIPITATION F. DO NOT LAUNCH THROUGH THUNDERSTORM DEBRIS CLOUDS, OR WITHIN 5 NM OF THUNDERSTORM DEBRIS CLOUDS NOT MONITORED BY A FIELD MILL NETWORK OR PRODUCING RADAR RETURNS GREATER THAN OR EQUAL TO 10 DBZ. DEBRIS CLOUD: IS ANY CLOUD LAYER OTHER THAN A THIN FIBROUS LAYER THAT HAS BECOME DETACHED FROM THE PARENT CUMULONIMBUS WITHIN 3 HOURS BEFORE LAUNCH. Rationale: Based on the known cloud types and conditions which produce natural and/or triggered lightning LCC RULE: GOOD SENSE RULE EVEN WHEN CONSTRAINTS ARE NOT VIOLATED, IF ANY OTHER HAZARDOUS CONDITIONS EXIST, THE LAUNCH WEATHER OFFICER WILL REPORT THE THREAT TO THE LAUNCH DIRECTOR. THE LAUNCH DIRECTOR MAY HOLD AT ANY TIME BASED ON THE INSTABILITY OF THE WEATHER. LCC RULE: SRB RECOVERY AREA DO NOT LAUNCH I F: A. SEA STATE EXCEEDS SEA STATE CODE 5 B. VISIBILITY LESS THAN 1.5 NM MANDATORY RECOVERY FOR ASSESSMENT OF SOLID ROCKET REDESIGN LCC RULE: RANGE SAFETY WEATHER RESTRICTIONS A. BLAST FOCUS (BASED ON SIMULATION USING WEATHER BALLOON AND WIND DATA) (1) IF MORE THAN 1 FATALITY PER 100,000 - HOLD OR SCRUB 4

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66 (2) VALUES BETWEEN 1 PER 100,000 AND 1 PER 1,000,000 REqUIRE EVALUATION BY ESMC COMMANDER B. CEILING AND VISIBILITY {REqUIRED TO AID RADAR ACqUISITIOM) - MUST HAVE CLEAR LINE OF SIGHT UP TO 4500 FEET C. LIGHTNING (PROTECTION OF RANGE DESTRUCT SYSTEM) SAME AS NATURAL AND TRIGGERED LIGHTNING CONSTRAINTS. PLEL>~#A~

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67 STS OPERATIONAL FLIGHT RULES ALL FLIGHTS FINAL MAY 9, 1988 PREFACE THIS PUBLICATION OF THE STS OPERATIONAL FLIGHT RULES, ALL FLIGHTS (dSC-12820) DATED MAY 9, 1988. REPLACES IN ITS ENTIRETY ALL PREVIOUS VERSIONS. THIS DOCUMENT AND THE FLIGHT SPECIFIC STS OPERATIONAL FLIGHT RULES ANNEX (USC-18308) ARE INTENDED TO BE USED IN CONJUNCTION WITH ONE ANOTHER. JSC-12820 STS OPERATIONAL FLIGHT RULES IS A CONTROLLED DOCUMENT FOR WHICH CHANGES ARE SUBJECT TO PROCEDURES DELINEATED IN APPENDIX ~ AND IS NOT TO BE REPRODUCED WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE CHIEF, FLIGHT DIRECTOR OFFICE, DAB, LYNDON B. JOHNSON SPACE CENTER. ORGANIZATIONS WITH COMMENTS, QUESTIONS OR SUGGESTIONS CONCERNING THESE FLIGHT RULES SHOULD DIRECT THEM TO DAB/C. L. GRUBY, FLIGHT DIRECTOR OfFICE, BUILDING 29, ROOM lOlB, NASA USE, HOUSTON, TEXAS 77058, TELEPHONE (713) 483-5558 (FTS 525-5558). APPROVED BY: ~ _~. G ~'~ ~ ~ :~/~N RICHARD H. KOHRS DEPUTY DIRECTOR, NATIONAL SPACE TRANSPORTATION SYSTEM PROGRAM at'. / l /~. 1~--~-~: ' TOMMY W. HOLLOWAY /~\ / LEUGENC F. K NZ CHIEF, FLIGHT DIRECTOR OFFICE ~ ~ DIRE tOR, MISSION OPERATIONS ROBERT L. CRIMPER ! DEPUTY DIRECTOR, NATIONAL SPACE TRANSPORTATION SYSTEM OPERATIONS /

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68 NASA- JOHNSON SPACE CENTER FLIGHT RULES RULE R _ 4-64 LANDING SITE WEATHER CRITERIA THE WEATHER ELEMENT LIMITS CONTAINED IN THIS RULE MUST BE SATISFIED WITH OBSERVATIONS AT THE GO/NO-GO DECISION TIME AND WITH THE FORE- CAST FOR LANDING TIME (EXCEPT PRELAUNCH EVALUATION OF THE FLIGHT DAY 1 PLS WILL ONLY BE BASED ON THE FORECAST). THE APPROACHES TO BOTH THE PRIME AND BACKUP RUNWAYS AT A GIVEN SITE MUST SATISFY THE CEILING, VISIBILITY, PRECIPITATION, AND THUNDERSTORM PROXIMITY LIMITS LISTED BELOW. WHENEVER AVAILABLE' A WEATHER RECONNAISSANCE FLIGHT WILL PROVIDE A LANDING SITE GO/NO-GO RECOMMENDATION. A. CEILING AND VISIBILITY LIMITS: VISIBILITY CEILING (NOT LESS THAN) (KFT) (SM L 1. EOM, NEXT PLS RTLS, TAL, AND ADA 10 (8 O) 7 (5 O) 2. ELS (ORBIT AND ENTRY PHASES) 10 (8 O) 5 3. TAL, ACLS, OR ELS (ASCENT PHASE) FOR MAIN ENGINE LIMITS MANAGEMENT (REF. RULE 5-TBD) OR ABORT GAP CLOSURE (REF. RULE 4-26H.3, PERFORMANCE BOUNDARIES) a. TACAN AND MLS OPERATING N/A N/A b. TACAN OPERATING, NO MLS 10 5 NOTES: l ~ APPLIES TO RUNWAY WITH MLS (REF. RULE 3-41, NAVAIDS PRELAUNCH REQUIREMENTS) AND REQUIRES WEATHER RECONNAISSANCE FLIGHT EVALUATION. FOR TAL AND ADA WITH MLS: VISIBILITY MAY BE AS LOW AS 5 SM ONLY IF THE FOLLOWING LANDING AIDS ARE VISIBLE AND PREDICTED TO REMAIN VISIBLE ON FINAL APPROACH (WEATHER RECONNAISSANCE FLIGHT EVALUATION): (a) PAPI's FROM 8K FT TO PREFLARE (b) BALL BARS FROM PREFLARE TO FINAL APPROACH _ _ ALL FINAL 5/9/88 I ~ t~lU OCR for page 62
69 NASA - JOHNSON SPACE CENTER FLIG HT RU LES R RULE _ 4-64 LANDING SITE WEATHER CRITERIA - Continued (Cons) A. CEILING AND VISIBILITY LIMITS - Continued The meteorological limits in this rule must be met with observations at the GO/NO-GO decision time and with the forecast for the landing time. This restriction is necessary to ensure weather uiolatiorts observed at the decision time (ground or weather reconnais sance) would not permit a GO decision. even if the forecast satisfies the limits. Conversely, if the forecast indicates a violation of the limits at landing time, a NO-GO decision will be made, independent of the current observations. Since the flight day 1 PLS landing time is 5 to 10 hours after launch, the forecast will only be used for the prelaunch flight day I PLS evaluation. The ceiling, risibility, precipitation, and thunderstorm proximity limits must be met for approaches to 60th the prime and backup runways, at a given site. This requirement exists because current forecasting capability cannot accurately ensure that a NO-GO condition to one of the backup runways would not result in a NO -GO condition at the prime runway by landing time. Surface wind limits are not required to be met at the backup runways, since the backup runway would only be required if an energy problem occurred dictating a runway redesignation. A ceiling is defined as cloud cover >0.5. There are two ceiling limits, one for runways with MLS and a higher limit for runways without MLS. Using MLS, the crew can main tain the approach path accurately to a lower altitude before beginning transition to visual cues (PAPl's, ball-bar, and runway markings). Eight thousand feet is the lowest layer or ceilingpermitted using MLS. For runways without MLS, the ceiling minimum is IOKft. Ceiling limits are established to ensure that the crew has sufficient time after breaking out of the cloud deck to acquire the runway and landing aids during pre-final and landing. _ _ TH IS RULE IS CONTINUED ON THE NEXT PAGE - ALL FINAL ~ | 5/9/88 1 TRAJECTORY, GUIDANCE MISS ION REV DATE SECTION ~4-54 _ SEEPAGE NO.

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70 NASA - JOHNSON SPACE CENTER FLIG HT RU LES R RULE _ 4-64 LANDING SITE WEATHER CRITERIA - Continued (Cons) A. CEILING AND VISIBILITY LIMITS - Concluded The surface visibility limits were established to correspond to the ceiling limits. Slant range visibility down the Orbiter glide slope is not measurable from the ground, nor is slant range a standard meteorological measurement. Therefore, the surface visibility and ceiling limits were established to provide acceptable slant range visibility. Restrictions to surface visibility include stroke, haze, fog, dust, and clouds. The 7 SM surface visibility limit generally applies for all landing conditions, with a couple exceptions. The 7 SM is the horizontal distance component from the runway threshold that correlates to the 10Kft altitude point on the outer glide slope. For AOA (ED W or NOR) or TAL aborts, the visibility requirements can be as low as 5 SM if the runway has an MLS and the weather reconnaissance aircraft verifies that the PAPI's are risible on the approach from 8K fit to preflare and the ball-bar is visible from preflare to final flare. This lower limit is allowed at the TAL or lakebed AOA sites where persistent low altitude/surface dust or smoke may greatly restrict the surface visibility; however, may not pose any significant limitation to crew "slant range" visibility during final approach to landing. This lower surface visibility can not be applied to sites which are prone to risibility limitations due to fog or other transient conditions. The 5 SM limit is the horizontal distance from the runway threshold that corresponds to the 8K fit altitude point on the outer glide slope. Five SM visibility is also the minimum limit used is assessing the usability of an ELS. Specific weather criteria are provided for decisions involving abort gap closure or main engine limits management during ascent phase. As documented in Rule 5-TBD and its rationale, in some case following SSME failure, main engine limits will be enabled at the earliest single-engin~ capability to reach a prime TAL or augmented contingency landing site (ACLS) (utilizing TAL guidance, event though the site itself may not be a program recognized TAL site). For this purpose, weather criteria may be relaxed, depending on landing aids status at the selected site, as a tradeoff to preclude exposure to SSME limits inhibited operation for any longer than necessary. In this situation, it is considered less risky to attempt a landing with potentially zero/zero conditions than to continue limits inhibited SSME operation, provided that both TACAN and MLS are available at the targeted site. If the site has only an operational TACAN, however, the same ceiling and visibility restrictions are applied as for orbitlentryphase ELS GO/NO-GO decisions. In the case of abort gap closure, it is likewise considered reasonable to attempt landing at a site with relatively poor weather conditions as long as the attempt carries a reasonable probability of success, when the alternative is an assured ditching situation. __ _ THIS RULE IS CONTINUED ON THE NEXT PAGE . ALL FINAL 5/9/88 TRAJECTORY, GUIDANCE MISS ION REV DATE SECTION 4-55 PAGE NO.

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71 NASA - JOHNSON SPACE CENTER FLIGHT RULES R RULE l 4-64 (Cons) LANDING SITE WEATHER CRITERIA - Continued B. SURFACE WIND LIMITS (DAYLIGHT LANDINGS): 1. THE SURFACE WIND LIMITS FOR ALL LANDING SITES ARE AS FOLLOWS: a. HEADWIND: s 25 KTS b. TAILWIND: < 10 KTS c. CROSSWIND: < 12 KTS NOTE: SURFACE WIND LIMITS REPRESENT PEAK WINDS, INCLUDING MAXIMUM GUSTS (GUSTS MUST BE < 8 KTS ABOVE THE AVERAGE WIND) 2. WITH ONE APU FAILED, SURFACE LIMITS CHANGE AS FOLLOWS: a. CROSSWIND < 10 KTS b. NOT GREATER THAN LIGHT TURBULENCE This table represents the not to be exceeded limits for wind components for the various landing sites. Head wind limits are established to ensure the Orbiter will land on the run- way with touchdown margin. Tailwinds affect the landing by causing longer touchdown ranges, loss of rollout margin, and higher brake energy. Crosswind limits are based upon Orbiter lateral control and tire wear. The limit of 12 KT peak crosswind corresponds to the point where the vehicle handling qualities becomes marginal based on Ames VMS simulations. Gusts of greater than 8 KT above the average/steady state wind corresponds to the I -sigma (statistical wind profile data; Shuttle Meteorological Group (SMG), Entry FTP 42) deviation for the maximum peak wind allowable (RSS of the peak headJcrosswind limits). The limit of c 8 KT was chosen in order to protect for the statistical gust factor (1-sigma) that reaches the headwind! crosswind limits. For one APU failed, the Orbiter is one failure away from having a loss of two APU's at touchdown. With two APU's down, the vehicle will have reduced flight control authority (loss of hydraulic power), braking, and nose wheel steering. In order to protect from this possible loss of control authority, crosswind peak limits are set at 10 KT for ad runways. Greater than light turbulence is not allowed for the same control loss reasons. THIS RULE IS CONTINUED ON THE NEXT PAGE . . FINAL 5/9/88 TRAJECTORY, GUIDANCE 4-56 . REV DATE ~SECTION _ ALL MISSION PAGE NO.

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72 NASA - JOHNSON SPACE CENTER FLIGHT RULES R RULE ~ 4-64 (Cons) ALL MISSION . . . _ LANDING SITE WEATHER CRITERIA - Continued Gusts, peak winds above the steady state or average wind, are limited to 8 KT. This 8 KT limit was derived from statistical data which indicated that when a 17 KT average wind is present, the peak wind or gust is-25 KT (our headwind limit). Loss of one APU invokes a crosswind and turbulence restriction. This part of the rule is meant to protect the Orbiter for the loss of a second APU. With two APU's down, the Orbiter will have reduced flight control, braking and nose wheel steering capability. (Refer to paragraph E for an explanation of the turbulence criteria.) C. SUN ANGLE LIMIT: SUN ON FINAL NOT WITHIN 10 DEG IN AZIMUTH AND O TO 20 DEG ELEVATION. These criteria was established to preclude the Sun from obstructing the crew's vision on final approach. D. PRECIPITATION AND THUNDERSTORM CRITERIA: 1. PRECIPITATION IS NOT ACCEPTABLE AT THE SURFACE OR ALOFT IN THE PROXIMITY OF THE ORBITER (SEE BELOW). PRECIPITATION INDICATIONS INCLUDE ANY OF THE FOLLOWING: a. VISIBLE RAIN OR VIRGA b. PRECIPITATION ECHO ON WEATHER RADAR c. CLOUD TYPES: CUMULONIMBUS OR CUMULUS CONGESTUS (TOWERING CUMULUS). The Orbiter is not to encounter precipitation on any approach due to decreased visibility andpotential damage to the TPS. Environmental design requirements for the Orbiter were based on the avoidance of in-Qightpenetration ofthunderstorms (ref: appendix 10-10, sol X, Space Shuttle Level II Program Specification). Undesirable aspects of thunderstorms include rain (TPS, structure), hail (TPS, structure, control), severe wind shear (structure), turbulence (control, performance, structure), and natural or triggered lightning (structure, electronic/software systems). A 10 n. mi. horizontal proximity distance was chosen based on research experience to minimize risk due to lightning, turbulence, and wind shear and to include forecast uncertainties. THIS RULE IS CONTINUED ON THE NEXT PAGE FINAL 5/9/88 TRAJECTORY, GUIDANCE 4-57 . . _ REV DATE SECTION PAGE NO.

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73 NASA - JOHNSON SPACE CENTER FLIGHT RULES R RULE 4-64 LANDING SITE WEATHER CRITERIA - Continued (Cons 2. THUNDERSTORM PROXIMITY (PRE-DEORBIT AND PRELAUNCH ADA): A SITE WILL BE NO-GO FOR LANDING IF THE THUNDERSTORM (INCLUDING ANVIL)' LIGHTNING, OR PRECIPITATION IS WITHIN 30 NM OF THE LANDING SITE. VERTICAL CLEARANCE FROM THESE PHENOMENA, AT THE 30 NM RANGE, MUST BE GREATER THAN 2 NM. ADDITIONALLY, DETACHED OPAQUE THUNDERSTORM ANVILS MUST NOT BE WITHIN 20 NM OF THE LANDING SITE, NOR WITHIN 10 NM OF THE APPROACH PATH OUT TO A RANGE OF 30 NM. For predeorbit or prelaunch AOA decisions (90 to 125 mire forecast), the 30 n. mi. clearance approximates the range to the runway for straight-in approaches at an altitude of 60K ft. Additionally, for these weather phenomena just outside the edge of the 30 n. mi. radius, at least 2 n. mi. vertical clearance must be maintained in order to avoid triggered lightning. 3. THUNDERSTORM PROXIMITY (PRELAUNCH RTLS AND TAL): A SITE WILL BE NO-GO FOR LANDING IF A THUNDERSTORM (INCLUDING ANVIL), LIGHTNING, OR PRECIPITATION IS WITHIN 20 NM OF THE LANDING SITE OR WITHIN 10 NM OF THE APPROACH PATH TO A RANGE OF 30 NM. VERTICAL CLEARANCE FROM THESE PHENOMENA MUST BE GREATER THAN 2 NM ALONG THE BORDER OF THE HORIZONTAL PROXIMITY BOUNDARY. For the prelaunch RTLS and TAL decisions (20 to 40 minute forecast), the 20 a. mi. radius clearance approximates a 10 n. mi. distance from each ofthe approach HAC's. This acceptable proximity distance is reduced fro no 30 n. mi. radius due to the shorter forecast period. The approach path between 20 n. mi. ar~d30 n. mi must also be protected by 10 a. mi. ADDITIONALLY, DETACHED OPAQUE THUNDERSTORM ANVILS MUST NOT BE WITHIN 10 NM OF THE LANDING SITE, NOR WITHIN 5 NM OF THE APPROACH PATH OUT TO A RANGE OF 30 NM. Detached opaque thunderstorm anvils haste the potential for triggered lightning and precipitation should the anc'`l be penetrated. Therefore, the proximity of the Orbiter from this phenomena is primarily determined by forecast uncertainty. For the 60-to-90 minute forecast, a 10 a. mi. margin will be maintained from the approach path and all of the heading alignment cones ( i.e.. 20 n. mi. radius from runway). Fear the 20-tO-4n minute forecast decisions. very little margin is prot~'cterl around the approach path: hence, the 10 n. mi. radius from the runway plus 5 n. mi. clearance along the flightpath. THIS RULE IS CONTINUED ON THE NEXT PAGE l A L | FINAL | 5/9/88 | TRAJECTORY, GUIDANCE I 4-58 MISSION REV | DATE T SECTION _ __ _ PAGE NO.

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74 NASA - JOHNSON SPACE CENTER FLIGHT RULES R RULE ~ 4-64 LANDING SITE WEATHER CRITERIA - Continued (Cons) 4. THUNDERSTORM AVOIDANCE AFTER COMMITTED FOR LANDING: A DISTANCE OF 5 NM HORIZONTALLY AND 2 NM ABOVE MUST BE MAINTAINED FROM A CUMULONIMBUS CLOUD, ANVIL OR ANY OTHER CONVECTIVE CLOUD (RAIN SHOWER) WHOSE TOP EXTENDS TO THE -10 CELSIUS HEIGHT. REAL-TIME THUNDERSTORM AVOIDANCE TECHNIQUES ARE LIMITED TO RUNWAY/HAC REDESIGNATION. NOTE: CLEARANCES WILL BE DETERMINED FROM EITHER RADAR PRECIPITATION ECHOES OR VISUAL OBSERVATIONS. The post-commitment avoidance clearances (5 n. mi. horizontal, 2 n. mi. vertical) were selected to reduce impact on energy management resulting from runway redesignation and maneuvers and at the same time ensure a reasonably low risk of a natural or triggered lightning strike. Prohibition of penetrating cumulonimbus, cumulus congestus, and opaque anvils is because of concern for triggered lightning and/or rain. Reference: Weather Rules Workshop at clSC/MSFC, October, 1987. Rule 4-62B, LANDING SITE SELECTION PRIORITIES, references this rule. E. TURBULENCE: NOT GREATER THAN MODERATE. Severe turbulence is undesirable due to controllability concerns. Turbulence information comes primarily from area pilot reports. The pilots' reports follow standard definitions for the intensity of the turbulence. The aircraft reaction for the different types of turbulence, as found in the DOD fl fight information handbook, are defined as follows: Light turbulence -- turbulence that momentarily causes slight, erratic changes in altitude andlor attitude. Moderate turbulence -- turbulence that causes changes in altitude and/or attitude, but with the aircraft remaining in positive control at all times. Severe turbulence -- turbulence that causes large, abrupt changes in altitude andlor attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control. THIS RULE IS CONTINUED ON THE NEXT PAGE _ . ALL FINAL 5/9/88 TRAJECTORY, GU IDANCE . MISSION REV DATE SECTION 4-59 i PAGE NO.

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- RULE 75 NASA - JOHNSON SPACE CENTER FLIGHT RULES 4-64 (Cons) LANDING SITE WEATHER CRITERIA - Continued F. ADDITIONAL NIGHT LANDING LIMITS: 1. WHEN AVAILABLE, A WEATHER RECONNAISSANCE AIRCRAFT WILL PROVIDE A GO/NO-GO RECOMMENDATION FOR THE LIGHT ATTENUATION Of THE LANDING AIDS AND THE TOUCHDOWN REGION. 2. CROSSWIND LIMIT IS c 10 KTS PEAK WIND FOR ALL NIGHT LANDING SITES. SURFACE WIND LIMITS INCLUDE MAXIMUM GUSTS (GUSTS MUST BE < 8 KTS ABOVE THE AVERAGE WIND) 3. WIND AND ATMOSPHERIC CONDITIONS MUST NOT REQUIRE USE OF CLOSE-IN AIMPOINT, EXCEPT WHERE CLOSE-IN AIMPOINT PAPI's ARE AVAILABLE. Because the aimpoin' markings and normal geographic visual cues are not visible at night, light attenuation ofthe landing aids and touchdown region area should be minimal. This evaluation ofthe light attenuation will primarily depend on the weather reconnaissance aircraft acceptability observations. If, however, an aircraft is unavailable, then visibility will be constrained by ground observations following the daylight visibility limits. The crosswind limits are lower for night landings because of the increased crew workload and visibility limitations beyond the runway edges. A runway requiring the close-in aimpoint is NO-GO unless there is a PAPI installed. Without the PAPI, the close-in aimpoint is not visible at night (Fit Tech 1, item 3). 4. FOR LAKEBED LANDINGS WITH ZERO fAULT TOLERANT MLS, MINIMUM CEILING LIMIT IS 20K FT. (REF. RULE 3-41B, NAVAIDS PRE LAUNCH REED I REMENTS, MLS ) . For lakehed landings only, single string MLS is acceptable if ceilings are greater than 20K ft. The increased ceiling provides additional time for the crew to compensate for navigation dispersions using visual cues. In addition. the larger area provided by the lakebed environment makes rratJigation dispersions resulting from the possible failure of the single-string MLS more tolerable. Rule2-1, PRE! AUNCH CO/NO-GO REQUIREMENTS, reference this rule. _ . FINAL 5/9/88 TRAJECTORY, GUIDANCE REV DATE SECTION . ALL 4-60 MISSION PAGE NO.

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76 NASA - JOHNSON SPACE CENTER FLIGHT RULES 4-64 (Coned) ALL MISSION LANDING SITE WEATHER CRITERIA - Concluded G. WET RUNWAY ACCEPTABILITY CONDITIONS THE FOLLOWING CONDITIONS WILL NO-GO USE OF A SPECIFIC RUNWAY: a. HARD SURfACE 1. STANDING WATER. b. LAKEBED 1. MOISTURE/STANDING WATER. 2. WET/SLUSHY SURFACE MATERIAL. 3. POTHOLES. c. ALL SURFACES 1. STRUCTURAL FAILURES (BREAKTHROUGH) 2. SNOW/ICE. NOTE: CONDITIONS ARE ASSESSED OVER THE ENTIRE PREPARED SURFACE OF RUNWAY Wet lakebed runways (more than a trace of rain) are not acceptable due to the possibility of hydroplaning and loss of brake effectiveness. Due to the large load bearing requirements of the Orbiter, structural failures are not acceptable on any surface type. Fissures or cracks which may lead to or be evidence of structural failures are not allowable. Wet/ slushy material is not acceptable due to the possibility of Orbiter damage from thrown surface material lifted up by the tires. Potholes are not acceptable owing to the possible tirelstrut damage caused by impact. For concrete surfaces, standing water may lead to hydroplaning conditions. Snow/ice is not acceptable for any runway surface as loss of traction results. Conditions are assessed over the entire prepared surface of the runway due to the uncertainty of where/when standing water may go. Reference Entry FTP 42. Rules 1-35RandJ,LANDINGSITES;2-lF.1 and3,LANDING SITE WEATHER CRITERIA; 2-31A and D, EXTENSION DAY REQUIREMENTS; 2-81A, EXTEN- SIONDAYGUIDELINES;341A,LANDINGSITEWEATHERCRITERIA; 4-2, LANDING SITE CONDITIONS; 4-26, PERFORMANCE BOUNDARIES; 4-62B, LANDING SITE SELECTION PRIORITIES; 4-65, DEORBIT PRIORITY FOR EOM WEATHER; 5-27, LIMIT SHUTDOWN CONTROL; and 8-60, GNC5GOINO-GO CRITERIA, reference this rule. . FINAL 5/9/88 TRAJECTORY' GUIDANCE REV DATE SECTION _ . 4-61 PAGE NO.

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77 NASA - JOHNSON SPACE CENTER FLIGHT RULES RULE R 4-65 DEORBIT PRIORITY FOR EOM WEATHER FORECAST VIOLATIONS (REf. RULE 4-64, LANDING SITE WEATHER CRITERIA) AT THE NOMINAL EOM TIME WILL RESULT IN SELECTION OF ONE OF THE FOLLOWING OPTIONS LISTED IN ORDER OF PRIORITY: A. DEORBIT TO PLS AT NOMINAL EOM TIME OR ONE ORBIT LATE TO ALTER- NATE RUNWAYS (IF REQUIRED FOR WINDS, SUN ANGLE, OR ISOLATED CLOUD COVERAGE). B. DEORBIT TO PLS EARLY ON EOM DAY. C. DEORBIT TO PLS DAILY OPPORTUNITY. D. DEORBIT TO PLS 24 HRS LATE. E. DEORBIT TO SLS AT NOMINAL EOM TIME. F. RELAX WEATHER CRITERIA. Deorbit to the primary landing site is always desirable due to convoy/ground operations support and crew familiarity. Options 1 to 4 provide apriority list of options to deorbit to the primary landing site. . Should it not be possible to deorbit to the primary site, the secondary landing site will be utilized (option 5J. Weather criteria will be relaxed real time should both the primary and secondary landing sites be unacceptable. Rule2-200, CONTINGENCYACTIONSUMMARY, references this rule. ALL FINAL 519/88 TRAJECTORY ~ GUIDANCE MISSION REV DATE SEMIS 4-62 PAGE NO.