Yeap your right FBJ. That is why we were flying at about 25ft through Iraq even a year after the Iraqi Army fell.
Here is info on the usual MANPADS that were encounter in Iraq:
SA-7 GRAIL 9K32M Strela-2
HN-5 (Hongying 5) China
Anza MKI - Pakistan
Ayn as Saqr - Egypt
Specifications
Date of Introduction 1972
Proliferation Worldwide
Crew 1
Launcher Name 9P54M
Length (m) 1.47
Diameter (mm) 70
Weight (kg) 4.71
Reaction Time 5-10 seconds (acquisition to fire)
Time Between Launches (sec) INA
Reload Time (sec) 6-10
Missile Name 9M32M
Max. Range 5,500 meters
Min. Range 500 meters
Max. Altitude 4,500 meters
Min. Altitude 18 meters
Length (m) 1.40
Diameter (mm) 70
Weight (kg) 9.97
Missile Speed (m/s) 580
Propulsion Solid fuel booster and solid fuel sustainer rocket motor.
Guidance Passive IR homing device (operating in the medium IR range)
Seeker Field of View 1.9°
Tracking Rate 6°/sec
Warhead Type HE
Warhead Weight (kg) 1.15
Fuze Type Contact (flush or grazing)
Self-Destruct (sec) 15
FIRE CONTROL Launcher has sighting device and a target acquisitionindicator.
The gunner visually identifies and acquires the target.
Gunner Field of View INA
Acquisition Range (m) INA
VARIANTS SA-N-5 Naval version
HN-5A Chinese version
Strela 2M/A Yugoslavian upgrade
Sakr Eye Egyptian upgrade
Mounted in several types of vehicles in four, six, and eight-tube launcher varieties.
Can be mounted on several helicopters (Mi-24, S-342 Gazelle)
SA-14 GREMLIN 9K34 Strela-3
Specifications
Designation 9K34 Strela-3
Date of Introduction 1978
Proliferation Worldwide
Crew 1
Launcher Name 9P59
Dimensions
Length (m) 1.40
Diameter (mm) 75
Weight (kg) 2.95
Reaction Time (sec) 14
Time Between Launches (sec) 35-40
Reload Time (sec) 25
Missile Name 9M36 or 9M36-1
Max. Range (m) 6,000
Min. Range (m) 600
Max. Altitude (m) 6,000
Min. Altitude (m) 50 Length (m) 1.4 m
Diameter (mm) 75 mm
Fin Span (mm) INA
Weight (kg) 10.3
Missile Speed (m/s) 600
Propulsion 2-stage solid-propellant rocket
Guidance passive IR homing
Seeker Field of View INA
Tracking Rate INA
Warhead Type Frag-HE
Warhead Weight (kg) 1.0
Fuze Type Contact/grazing
Self-Destruct (sec) 14-17
FIRE CONTROL Sights w/Magnification
Launch tube has simple sights
Gunner Field of View ( o ) INA
Acquisition Range (m) INA
IFF Yes
VARIANTS Igla 9M39 (SA-N-8) Naval version
SA-16 GIMLET Igla-1 9K310
Specifications
Maximum Speed 2+ Mach
Effective Altitude 3,500 m
Effective Range 500 -- 5,000 m
Altitude 10-3500 m
Warhead HE 2kg
Guidance passive 2-color IR and
UV homing
Fuze Contact and graze
Kill Radius Unknown
SA-18 GROUSE Igla 9K38
SA-N-10 GROUSE Igla-M
Specifications
Contractor
Entered Service
Total length
Diameter
Wingspan
Weight
Warhead Weight
Propulsion
Maximum Speed
Maximum effective range 5200 meters
altitude, (m) 10-3500
Guidance mode passive IR homing
emplace/displace time 13 sec
Single-shot hit probability
So as you can see the yes the MANPADS do not have the range or alltitude to reach a high flying aircraft however these SAMs can reach aircraft at these alltitudes: SA-1: 60,000ft to 80,000ft, SA-2: 100m to 100km alltitude, SA-4: 100m to 27,000m, SA-6: 80m to 11,000m. These are just the older missles, what about the new stuff. As you can see even a B-52 flying at 50,000ft is in direct threat of being shot down by SAMs. As FBJ said most B-52 missions now call for low alltitude flying.
The reason for this, believe it or not, is visability and below the radar.